diff --git a/runtime/observatory/lib/object_graph.dart b/runtime/observatory/lib/object_graph.dart
index e89d074..3ccc6c3 100644
--- a/runtime/observatory/lib/object_graph.dart
+++ b/runtime/observatory/lib/object_graph.dart
@@ -359,7 +359,7 @@
     var next = _graph._mergedDomNext;
     var cids = _graph._cids;
 
-    var domChildren = [];
+    var domChildren = <MergedObjectVertex>[];
     var prev = SENTINEL;
     var child = _graph._mergedDomHead[_id];
     // Walk the list of children and look for the representative objects, i.e.
diff --git a/runtime/observatory/lib/src/elements/debugger.dart b/runtime/observatory/lib/src/elements/debugger.dart
index a9f843a..1c70579 100644
--- a/runtime/observatory/lib/src/elements/debugger.dart
+++ b/runtime/observatory/lib/src/elements/debugger.dart
@@ -36,7 +36,7 @@
 abstract class DebuggerCommand extends Command {
   ObservatoryDebugger debugger;
 
-  DebuggerCommand(this.debugger, name, children) : super(name, children);
+  DebuggerCommand(this.debugger, name, List<Command> children) : super(name, children);
 
   String get helpShort;
   String get helpLong;
@@ -46,7 +46,7 @@
 // provided by the cli library.
 class HelpCommand extends DebuggerCommand {
   HelpCommand(Debugger debugger)
-      : super(debugger, 'help', [
+      : super(debugger, 'help', <Command>[
           new HelpHotkeysCommand(debugger),
         ]);
 
@@ -62,7 +62,7 @@
     var con = debugger.console;
     if (args.length == 0) {
       // Print list of all top-level commands.
-      var commands = debugger.cmd.matchCommand([], false);
+      var commands = debugger.cmd.matchCommand(<String>[], false);
       commands.sort((a, b) => a.name.compareTo(b.name));
       con.print('List of commands:\n');
       for (DebuggerCommand command in commands) {
@@ -92,7 +92,7 @@
         con.printBold(_nameAndAlias(command));
         con.print(command.helpLong);
 
-        var newArgs = [];
+        var newArgs = <String>[];
         newArgs.addAll(args.take(args.length - 1));
         newArgs.add(command.name);
         newArgs.add('');
@@ -129,7 +129,7 @@
 }
 
 class HelpHotkeysCommand extends DebuggerCommand {
-  HelpHotkeysCommand(Debugger debugger) : super(debugger, 'hotkeys', []);
+  HelpHotkeysCommand(Debugger debugger) : super(debugger, 'hotkeys', <Command>[]);
 
   Future run(List<String> args) {
     var con = debugger.console;
@@ -160,7 +160,7 @@
 }
 
 class PrintCommand extends DebuggerCommand {
-  PrintCommand(Debugger debugger) : super(debugger, 'print', []) {
+  PrintCommand(Debugger debugger) : super(debugger, 'print', <Command>[]) {
     alias = 'p';
   }
 
@@ -193,7 +193,7 @@
 }
 
 class DownCommand extends DebuggerCommand {
-  DownCommand(Debugger debugger) : super(debugger, 'down', []);
+  DownCommand(Debugger debugger) : super(debugger, 'down', <Command>[]);
 
   Future run(List<String> args) {
     int count = 1;
@@ -227,7 +227,7 @@
 }
 
 class UpCommand extends DebuggerCommand {
-  UpCommand(Debugger debugger) : super(debugger, 'up', []);
+  UpCommand(Debugger debugger) : super(debugger, 'up', <Command>[]);
 
   Future run(List<String> args) {
     int count = 1;
@@ -261,7 +261,7 @@
 }
 
 class FrameCommand extends DebuggerCommand {
-  FrameCommand(Debugger debugger) : super(debugger, 'frame', []) {
+  FrameCommand(Debugger debugger) : super(debugger, 'frame', <Command>[]) {
     alias = 'f';
   }
 
@@ -295,7 +295,7 @@
 }
 
 class PauseCommand extends DebuggerCommand {
-  PauseCommand(Debugger debugger) : super(debugger, 'pause', []);
+  PauseCommand(Debugger debugger) : super(debugger, 'pause', <Command>[]);
 
   Future run(List<String> args) {
     return debugger.pause();
@@ -311,7 +311,7 @@
 }
 
 class ContinueCommand extends DebuggerCommand {
-  ContinueCommand(Debugger debugger) : super(debugger, 'continue', []) {
+  ContinueCommand(Debugger debugger) : super(debugger, 'continue', <Command>[]) {
     alias = 'c';
   }
 
@@ -330,7 +330,7 @@
 }
 
 class SmartNextCommand extends DebuggerCommand {
-  SmartNextCommand(Debugger debugger) : super(debugger, 'next', []) {
+  SmartNextCommand(Debugger debugger) : super(debugger, 'next', <Command>[]) {
     alias = 'n';
   }
 
@@ -352,7 +352,7 @@
 }
 
 class SyncNextCommand extends DebuggerCommand {
-  SyncNextCommand(Debugger debugger) : super(debugger, 'next-sync', []);
+  SyncNextCommand(Debugger debugger) : super(debugger, 'next-sync', <Command>[]);
 
   Future run(List<String> args) {
     return debugger.syncNext();
@@ -368,7 +368,7 @@
 }
 
 class AsyncNextCommand extends DebuggerCommand {
-  AsyncNextCommand(Debugger debugger) : super(debugger, 'next-async', []);
+  AsyncNextCommand(Debugger debugger) : super(debugger, 'next-async', <Command>[]);
 
   Future run(List<String> args) {
     return debugger.asyncNext();
@@ -384,7 +384,7 @@
 }
 
 class StepCommand extends DebuggerCommand {
-  StepCommand(Debugger debugger) : super(debugger, 'step', []) {
+  StepCommand(Debugger debugger) : super(debugger, 'step', <Command>[]) {
     alias = 's';
   }
 
@@ -406,7 +406,7 @@
 }
 
 class RewindCommand extends DebuggerCommand {
-  RewindCommand(Debugger debugger) : super(debugger, 'rewind', []);
+  RewindCommand(Debugger debugger) : super(debugger, 'rewind', <Command>[]);
 
   Future run(List<String> args) async {
     try {
@@ -443,7 +443,7 @@
   final M.IsolateRepository _isolates;
 
   ReloadCommand(Debugger debugger, this._isolates)
-      : super(debugger, 'reload', []);
+      : super(debugger, 'reload', <Command>[]);
 
   Future run(List<String> args) async {
     try {
@@ -477,7 +477,7 @@
 }
 
 class ClsCommand extends DebuggerCommand {
-  ClsCommand(Debugger debugger) : super(debugger, 'cls', []) {}
+  ClsCommand(Debugger debugger) : super(debugger, 'cls', <Command>[]) {}
 
   Future run(List<String> args) {
     debugger.console.clear();
@@ -493,7 +493,7 @@
 }
 
 class LogCommand extends DebuggerCommand {
-  LogCommand(Debugger debugger) : super(debugger, 'log', []);
+  LogCommand(Debugger debugger) : super(debugger, 'log', <Command>[]);
 
   Future run(List<String> args) async {
     if (args.length == 0) {
@@ -560,7 +560,7 @@
 }
 
 class FinishCommand extends DebuggerCommand {
-  FinishCommand(Debugger debugger) : super(debugger, 'finish', []);
+  FinishCommand(Debugger debugger) : super(debugger, 'finish', <Command>[]);
 
   Future run(List<String> args) {
     if (debugger.isolatePaused()) {
@@ -591,7 +591,7 @@
 }
 
 class SetCommand extends DebuggerCommand {
-  SetCommand(Debugger debugger) : super(debugger, 'set', []);
+  SetCommand(Debugger debugger) : super(debugger, 'set', <Command>[]);
 
   static var _boeValues = ['All', 'None', 'Unhandled'];
   static var _boolValues = ['false', 'true'];
@@ -737,7 +737,7 @@
 }
 
 class BreakCommand extends DebuggerCommand {
-  BreakCommand(Debugger debugger) : super(debugger, 'break', []);
+  BreakCommand(Debugger debugger) : super(debugger, 'break', <Command>[]);
 
   Future run(List<String> args) async {
     if (args.length > 1) {
@@ -821,7 +821,7 @@
 }
 
 class ClearCommand extends DebuggerCommand {
-  ClearCommand(Debugger debugger) : super(debugger, 'clear', []);
+  ClearCommand(Debugger debugger) : super(debugger, 'clear', <Command>[]);
 
   Future run(List<String> args) async {
     if (args.length > 1) {
@@ -908,7 +908,7 @@
 
 // TODO(turnidge): Add argument completion.
 class DeleteCommand extends DebuggerCommand {
-  DeleteCommand(Debugger debugger) : super(debugger, 'delete', []);
+  DeleteCommand(Debugger debugger) : super(debugger, 'delete', <Command>[]);
 
   Future run(List<String> args) {
     if (args.length < 1) {
@@ -948,7 +948,7 @@
 
 class InfoBreakpointsCommand extends DebuggerCommand {
   InfoBreakpointsCommand(Debugger debugger)
-      : super(debugger, 'breakpoints', []);
+      : super(debugger, 'breakpoints', <Command>[]);
 
   Future run(List<String> args) async {
     if (debugger.isolate.breakpoints.isEmpty) {
@@ -975,7 +975,7 @@
 }
 
 class InfoFrameCommand extends DebuggerCommand {
-  InfoFrameCommand(Debugger debugger) : super(debugger, 'frame', []);
+  InfoFrameCommand(Debugger debugger) : super(debugger, 'frame', <Command>[]);
 
   Future run(List<String> args) {
     if (args.length > 0) {
@@ -995,7 +995,7 @@
 
 class IsolateCommand extends DebuggerCommand {
   IsolateCommand(Debugger debugger)
-      : super(debugger, 'isolate', [
+      : super(debugger, 'isolate', <Command>[
           new IsolateListCommand(debugger),
           new IsolateNameCommand(debugger),
         ]) {
@@ -1077,7 +1077,7 @@
 }
 
 class IsolateListCommand extends DebuggerCommand {
-  IsolateListCommand(Debugger debugger) : super(debugger, 'list', []);
+  IsolateListCommand(Debugger debugger) : super(debugger, 'list', <Command>[]);
 
   Future run(List<String> args) async {
     if (debugger.vm == null) {
@@ -1123,7 +1123,7 @@
 }
 
 class IsolateNameCommand extends DebuggerCommand {
-  IsolateNameCommand(Debugger debugger) : super(debugger, 'name', []);
+  IsolateNameCommand(Debugger debugger) : super(debugger, 'name', <Command>[]);
 
   Future run(List<String> args) {
     if (args.length != 1) {
@@ -1142,7 +1142,7 @@
 
 class InfoCommand extends DebuggerCommand {
   InfoCommand(Debugger debugger)
-      : super(debugger, 'info', [
+      : super(debugger, 'info', <Command>[
           new InfoBreakpointsCommand(debugger),
           new InfoFrameCommand(debugger)
         ]);
@@ -1160,7 +1160,7 @@
 }
 
 class RefreshStackCommand extends DebuggerCommand {
-  RefreshStackCommand(Debugger debugger) : super(debugger, 'stack', []);
+  RefreshStackCommand(Debugger debugger) : super(debugger, 'stack', <Command>[]);
 
   Future run(List<String> args) {
     return debugger.refreshStack();
@@ -1175,7 +1175,7 @@
 
 class RefreshCommand extends DebuggerCommand {
   RefreshCommand(Debugger debugger)
-      : super(debugger, 'refresh', [
+      : super(debugger, 'refresh', <Command>[
           new RefreshStackCommand(debugger),
         ]);
 
@@ -1193,7 +1193,7 @@
 }
 
 class VmListCommand extends DebuggerCommand {
-  VmListCommand(Debugger debugger) : super(debugger, 'list', []);
+  VmListCommand(Debugger debugger) : super(debugger, 'list', <Command>[]);
 
   Future run(List<String> args) async {
     if (args.length > 0) {
@@ -1235,7 +1235,7 @@
 }
 
 class VmNameCommand extends DebuggerCommand {
-  VmNameCommand(Debugger debugger) : super(debugger, 'name', []);
+  VmNameCommand(Debugger debugger) : super(debugger, 'name', <Command>[]);
 
   Future run(List<String> args) async {
     if (args.length != 1) {
@@ -1258,7 +1258,7 @@
 
 class VmCommand extends DebuggerCommand {
   VmCommand(Debugger debugger)
-      : super(debugger, 'vm', [
+      : super(debugger, 'vm', <Command>[
           new VmListCommand(debugger),
           new VmNameCommand(debugger),
         ]);
diff --git a/runtime/observatory/lib/src/elements/function_view.dart b/runtime/observatory/lib/src/elements/function_view.dart
index 3ac4629..57d775a 100644
--- a/runtime/observatory/lib/src/elements/function_view.dart
+++ b/runtime/observatory/lib/src/elements/function_view.dart
@@ -169,19 +169,19 @@
   }
 
   List<Element> _createMenu() {
-    final menu = [
+    final menu = <Element>[
       new NavTopMenuElement(queue: _r.queue),
       new NavVMMenuElement(_vm, _events, queue: _r.queue),
       new NavIsolateMenuElement(_isolate, _events, queue: _r.queue)
     ];
     if (_library != null) {
-      menu.add(new NavLibraryMenuElement(_isolate, _function.dartOwner,
+      menu.add(new NavLibraryMenuElement(_isolate, _library,
           queue: _r.queue));
     } else if (_function.dartOwner is M.ClassRef) {
       menu.add(new NavClassMenuElement(_isolate, _function.dartOwner,
           queue: _r.queue));
     }
-    menu.addAll([
+    menu.addAll(<Element>[
       navMenu(_function.name),
       new NavRefreshElement(queue: _r.queue)
         ..onRefresh.listen((e) {
diff --git a/runtime/observatory/lib/src/elements/heap_map.dart b/runtime/observatory/lib/src/elements/heap_map.dart
index 2c12234..6db1ce8 100644
--- a/runtime/observatory/lib/src/elements/heap_map.dart
+++ b/runtime/observatory/lib/src/elements/heap_map.dart
@@ -169,12 +169,12 @@
     return [rng.nextInt(128), rng.nextInt(128), rng.nextInt(128), 255];
   }
 
-  String _classNameAt(Point<int> point) {
+  String _classNameAt(Point<num> point) {
     var color = new PixelReference(_fragmentationData, point).color;
     return _classIdToName[_colorToClassId[_packColor(color)]];
   }
 
-  ObjectInfo _objectAt(Point<int> point) {
+  ObjectInfo _objectAt(Point<num> point) {
     if (_fragmentation == null || _canvas == null) {
       return null;
     }
@@ -302,13 +302,13 @@
   var _dataIndex;
   static const NUM_COLOR_COMPONENTS = 4;
 
-  PixelReference(ImageData data, Point<int> point)
+  PixelReference(ImageData data, Point<num> point)
       : _data = data,
         _dataIndex = (point.y * data.width + point.x) * NUM_COLOR_COMPONENTS;
 
   PixelReference._fromDataIndex(this._data, this._dataIndex);
 
-  Point<int> get point => new Point(index % _data.width, index ~/ _data.width);
+  Point<num> get point => new Point(index % _data.width, index ~/ _data.width);
 
   void set color(Iterable<int> color) {
     _data.data.setRange(_dataIndex, _dataIndex + NUM_COLOR_COMPONENTS, color);
diff --git a/runtime/observatory/lib/src/elements/heap_snapshot.dart b/runtime/observatory/lib/src/elements/heap_snapshot.dart
index 9fabccb..3e6e455 100644
--- a/runtime/observatory/lib/src/elements/heap_snapshot.dart
+++ b/runtime/observatory/lib/src/elements/heap_snapshot.dart
@@ -430,8 +430,8 @@
     return const [];
   }
 
-  void _updateDominator(
-      HtmlElement element, M.HeapSnapshotDominatorNode node, int depth) {
+  void _updateDominator(HtmlElement element, nodeDynamic, int depth) {
+    M.HeapSnapshotDominatorNode node = nodeDynamic;
     element.children[0].text = Utils.formatSize(node.retainedSize);
     _updateLines(element.children[1].children, depth);
     if (_getChildrenDominator(node).isNotEmpty) {
@@ -463,8 +463,8 @@
     }
   }
 
-  void _updateMergedDominator(
-      HtmlElement element, M.HeapSnapshotMergedDominatorNode node, int depth) {
+  void _updateMergedDominator(HtmlElement element, nodeDynamic, int depth) {
+    M.HeapSnapshotMergedDominatorNode node = nodeDynamic;
     element.children[0].text = Utils.formatSize(node.retainedSize);
     _updateLines(element.children[1].children, depth);
     if (_getChildrenMergedDominator(node).isNotEmpty) {
diff --git a/runtime/observatory/lib/src/elements/nav/notify.dart b/runtime/observatory/lib/src/elements/nav/notify.dart
index f3cd50e..6b22f32 100644
--- a/runtime/observatory/lib/src/elements/nav/notify.dart
+++ b/runtime/observatory/lib/src/elements/nav/notify.dart
@@ -80,7 +80,7 @@
     return true;
   }
 
-  HtmlElement _toElement(M.Notification notification) {
+  Element _toElement(M.Notification notification) {
     if (notification is M.EventNotification) {
       return new NavNotifyEventElement(notification.event, queue: _r.queue)
         ..onDelete.listen((_) => _repository.delete(notification));
diff --git a/runtime/observatory/lib/src/elements/nav/notify_exception.dart b/runtime/observatory/lib/src/elements/nav/notify_exception.dart
index 8b75dca..58836f6 100644
--- a/runtime/observatory/lib/src/elements/nav/notify_exception.dart
+++ b/runtime/observatory/lib/src/elements/nav/notify_exception.dart
@@ -10,7 +10,7 @@
 import 'package:observatory/models.dart' show ConnectionException;
 
 class ExceptionDeleteEvent {
-  final Exception exception;
+  final dynamic exception;
   final StackTrace stacktrace;
 
   ExceptionDeleteEvent(this.exception, {this.stacktrace});
@@ -28,13 +28,13 @@
       new StreamController<ExceptionDeleteEvent>.broadcast();
   Stream<ExceptionDeleteEvent> get onDelete => _onDelete.stream;
 
-  Exception _exception;
+  dynamic _exception;
   StackTrace _stacktrace;
 
-  Exception get exception => _exception;
+  dynamic get exception => _exception;
   StackTrace get stacktrace => _stacktrace;
 
-  factory NavNotifyExceptionElement(Exception exception,
+  factory NavNotifyExceptionElement(dynamic exception,
       {StackTrace stacktrace: null, RenderingQueue queue}) {
     assert(exception != null);
     NavNotifyExceptionElement e = document.createElement(tag.name);
diff --git a/runtime/observatory/lib/src/elements/persistent_handles.dart b/runtime/observatory/lib/src/elements/persistent_handles.dart
index 92d3ee5..57f6196 100644
--- a/runtime/observatory/lib/src/elements/persistent_handles.dart
+++ b/runtime/observatory/lib/src/elements/persistent_handles.dart
@@ -162,17 +162,23 @@
     }
     switch (_sortingDirection) {
       case _SortingDirection.ascending:
-        return (a, b) => getter(a).compareTo(getter(b));
+        int sort(M.WeakPersistentHandle a, M.WeakPersistentHandle b) {
+          return getter(a).compareTo(getter(b));
+        }
+        return sort;
       case _SortingDirection.descending:
-        return (a, b) => getter(b).compareTo(getter(a));
+        int sort(M.WeakPersistentHandle a, M.WeakPersistentHandle b) {
+          return getter(b).compareTo(getter(a));
+        }
+        return sort;
     }
   }
 
-  static Element _createLine() => new DivElement()
+  static HtmlElement _createLine() => new DivElement()
     ..classes = ['collection-item']
     ..text = 'object';
 
-  static Element _createWeakLine() => new DivElement()
+  static HtmlElement _createWeakLine() => new DivElement()
     ..classes = ['weak-item']
     ..children = <Element>[
       new SpanElement()
@@ -231,7 +237,8 @@
     _r.dirty();
   }
 
-  void _updateWeakLine(Element e, M.WeakPersistentHandle item, index) {
+  void _updateWeakLine(Element e, itemDynamic, index) {
+    M.WeakPersistentHandle item = itemDynamic;
     e.children[0].text = Utils.formatSize(_getExternalSize(item));
     e.children[1].text = '${_getPeer(item)}';
     e.children[2] = anyRef(_isolate, item.object, _objects, queue: _r.queue)
@@ -241,7 +248,8 @@
       ..title = '${_getFinalizerCallback(item)}';
   }
 
-  void _updateLine(Element e, M.PersistentHandle item, index) {
+  void _updateLine(Element e, itemDynamic, index) {
+    M.PersistentHandle item = itemDynamic;
     e.children = <Element>[
       anyRef(_isolate, item.object, _objects, queue: _r.queue)
         ..classes = ['object']
diff --git a/runtime/observatory/lib/src/elements/retaining_path.dart b/runtime/observatory/lib/src/elements/retaining_path.dart
index 1c1b2f6..a72c728 100644
--- a/runtime/observatory/lib/src/elements/retaining_path.dart
+++ b/runtime/observatory/lib/src/elements/retaining_path.dart
@@ -87,7 +87,7 @@
       return [new SpanElement()..text = 'Loading'];
     }
 
-    var elements = new List();
+    var elements = new List<Element>();
     bool first = true;
     for (var item in _path.elements) {
       elements.add(_createItem(item, first));
diff --git a/runtime/observatory/lib/src/elements/script_inset.dart b/runtime/observatory/lib/src/elements/script_inset.dart
index ef8e767..28ecc97 100644
--- a/runtime/observatory/lib/src/elements/script_inset.dart
+++ b/runtime/observatory/lib/src/elements/script_inset.dart
@@ -150,7 +150,7 @@
   int _startLine;
   int _endLine;
 
-  Map<int, List<S.ServiceMap>> _rangeMap = {};
+  Map/*<int, List<S.ServiceMap>>*/ _rangeMap = {};
   Set _callSites = new Set<S.CallSite>();
   Set _possibleBreakpointLines = new Set<int>();
   Map<int, ScriptLineProfile> _profileMap = {};
diff --git a/runtime/observatory/lib/src/heap_snapshot/heap_snapshot.dart b/runtime/observatory/lib/src/heap_snapshot/heap_snapshot.dart
index c14bff7b..9b90eaa 100644
--- a/runtime/observatory/lib/src/heap_snapshot/heap_snapshot.dart
+++ b/runtime/observatory/lib/src/heap_snapshot/heap_snapshot.dart
@@ -136,16 +136,16 @@
 class HeapSnapshotDominatorNode implements M.HeapSnapshotDominatorNode {
   final ObjectVertex v;
   final S.Isolate isolate;
-  S.HeapObject _preloaded;
+  S.ServiceObject _preloaded;
 
   bool get isStack => v.isStack;
 
-  Future<S.HeapObject> get object {
+  Future<S.ServiceObject> get object {
     if (_preloaded != null) {
       return new Future.value(_preloaded);
     } else {
       return isolate.getObjectByAddress(v.address).then((S.ServiceObject obj) {
-        return _preloaded = obj as S.HeapObject;
+        return _preloaded = obj;
       });
     }
   }
diff --git a/runtime/observatory/lib/src/models/objects/field.dart b/runtime/observatory/lib/src/models/objects/field.dart
index 8ac61ee..d0d1221 100644
--- a/runtime/observatory/lib/src/models/objects/field.dart
+++ b/runtime/observatory/lib/src/models/objects/field.dart
@@ -32,7 +32,7 @@
 
 abstract class Field extends Object implements FieldRef {
   /// [optional] The value of this field, if the field is static.
-  InstanceRef get staticValue;
+  ObjectRef get staticValue;
 
   /// [optional] The location of this field in the source code.
   SourceLocation get location;
diff --git a/runtime/observatory/lib/src/service/object.dart b/runtime/observatory/lib/src/service/object.dart
index 2663949..826897c 100644
--- a/runtime/observatory/lib/src/service/object.dart
+++ b/runtime/observatory/lib/src/service/object.dart
@@ -106,7 +106,7 @@
 }
 
 /// A [ServiceObject] represents a persistent object within the vm.
-abstract class ServiceObject {
+abstract class ServiceObject implements M.ObjectRef {
   static int LexicalSortName(ServiceObject o1, ServiceObject o2) {
     return o1.name.compareTo(o2.name);
   }
@@ -1173,17 +1173,18 @@
   final Iterable<InboundReference> elements;
 
   InboundReferences(ServiceMap map)
-      : this.elements =
-            map['references'].map((rmap) => new InboundReference(rmap));
+      : this.elements = map['references']
+            .map<InboundReference>((rmap) => new InboundReference(rmap))
+            .toList();
 }
 
 class InboundReference implements M.InboundReference {
-  final HeapObject source;
+  final ServiceObject /*HeapObject*/ source;
   final Instance parentField;
   final int parentListIndex;
   final int parentWordOffset;
 
-  InboundReference(ServiceMap map)
+  InboundReference(Map map)
       : source = map['source'],
         parentField = map['parentField'],
         parentListIndex = map['parentListIndex'],
@@ -1194,17 +1195,18 @@
   final Iterable<RetainingPathItem> elements;
 
   RetainingPath(ServiceMap map)
-      : this.elements =
-            map['elements'].map((rmap) => new RetainingPathItem(rmap));
+      : this.elements = map['elements']
+            .map<RetainingPathItem>((rmap) => new RetainingPathItem(rmap))
+            .toList();
 }
 
 class RetainingPathItem implements M.RetainingPathItem {
-  final HeapObject source;
+  final ServiceObject /*HeapObject*/ source;
   final Instance parentField;
   final int parentListIndex;
   final int parentWordOffset;
 
-  RetainingPathItem(ServiceMap map)
+  RetainingPathItem(Map map)
       : source = map['value'],
         parentField = map['parentField'],
         parentListIndex = map['parentListIndex'],
@@ -1215,7 +1217,8 @@
   final Iterable<Port> elements;
 
   Ports(ServiceMap map)
-      : this.elements = map['ports'].map((rmap) => new Port(rmap));
+      : this.elements =
+            map['ports'].map<Port>((rmap) => new Port(rmap)).toList();
 }
 
 class Port implements M.Port {
@@ -1233,10 +1236,11 @@
 
   PersistentHandles(ServiceMap map)
       : this.elements = map['persistentHandles']
-            .map<PersistentHandle>((rmap) => new PersistentHandle(rmap)),
+            .map<PersistentHandle>((rmap) => new PersistentHandle(rmap))
+            .toList(),
         this.weakElements = map['weakPersistentHandles']
-            .map<WeakPersistentHandle>(
-                (rmap) => new WeakPersistentHandle(rmap));
+            .map<WeakPersistentHandle>((rmap) => new WeakPersistentHandle(rmap))
+            .toList();
 }
 
 class PersistentHandle implements M.PersistentHandle {
@@ -1983,13 +1987,14 @@
     return invokeRpc('_getInstances', params);
   }
 
-  Future<HeapObject> getObjectByAddress(String address, [bool ref = true]) {
+  Future<ServiceObject /*HeapObject*/ > getObjectByAddress(String address,
+      [bool ref = true]) {
     Map params = {
       'address': address,
       'ref': ref,
     };
     return invokeRpc('_getObjectByAddress', params)
-        .then((result) => result as HeapObject);
+        .then((result) => result as ServiceObject);
   }
 
   final Map<String, ServiceMetric> dartMetrics = <String, ServiceMetric>{};
@@ -2121,21 +2126,22 @@
 }
 
 /// A [DartError] is peered to a Dart Error object.
-class DartError extends ServiceObject implements M.Error {
+class DartError extends HeapObject implements M.Error {
   DartError._empty(ServiceObject owner) : super._empty(owner);
 
   M.ErrorKind kind;
-  final M.ClassRef clazz = null;
-  final int size = null;
   String message;
   Instance exception;
   Instance stacktrace;
 
   void _update(Map map, bool mapIsRef) {
+    _upgradeCollection(map, owner);
+    super._update(map, mapIsRef);
+
     message = map['message'];
     kind = stringToErrorKind(map['kind']);
-    exception = new ServiceObject._fromMap(owner, map['exception']);
-    stacktrace = new ServiceObject._fromMap(owner, map['stacktrace']);
+    exception = map['exception'];
+    stacktrace = map['stacktrace'];
     name = 'DartError($message)';
     vmName = name;
   }
@@ -3310,7 +3316,7 @@
   bool isStatic;
   bool isFinal;
   bool isConst;
-  Instance staticValue;
+  ServiceObject staticValue;
   String name;
   String vmName;
 
@@ -3960,7 +3966,9 @@
     if (mapIsRef) {
       return;
     }
-    entries = map['_entries'].map((map) => new ObjectPoolEntry(map));
+    entries = map['_entries']
+        .map<ObjectPoolEntry>((map) => new ObjectPoolEntry(map))
+        .toList();
   }
 }
 
@@ -4120,7 +4128,7 @@
       return;
     }
     count = map['totalCount'];
-    samples = map['samples'];
+    samples = new List<HeapObject>.from(map['samples']);
   }
 }
 
@@ -4303,12 +4311,15 @@
           return;
         }
         // Load the script and then update descriptors.
-        script.load().then(_updateDescriptors);
+        script.load().then((_) => _updateDescriptors(script));
       });
       return;
     }
-    // Load the script and then update descriptors.
-    function.location.script.load().then(_updateDescriptors);
+    {
+      // Load the script and then update descriptors.
+      var script = function.location.script;
+      script.load().then((_) => _updateDescriptors(script));
+    }
   }
 
   /// Reload [this]. Returns a future which completes to [this] or an
diff --git a/runtime/observatory/tests/service/break_on_activation_test.dart b/runtime/observatory/tests/service/break_on_activation_test.dart
index 904ce63..1b56913 100644
--- a/runtime/observatory/tests/service/break_on_activation_test.dart
+++ b/runtime/observatory/tests/service/break_on_activation_test.dart
@@ -65,7 +65,7 @@
     valueOfField(String name) async {
       var field = rootLib.variables.singleWhere((v) => v.name == name);
       await field.load();
-      return field.staticValue;
+      return field.staticValue as Instance;
     }
 
     var r1Ref = await valueOfField('r1');
@@ -109,7 +109,7 @@
     valueOfField(String name) async {
       var field = rootLib.variables.singleWhere((v) => v.name == name);
       await field.load();
-      return field.staticValue;
+      return field.staticValue as Instance;
     }
 
     var r1Ref = await valueOfField('r1_named');
@@ -153,7 +153,7 @@
     valueOfField(String name) async {
       var field = rootLib.variables.singleWhere((v) => v.name == name);
       await field.load();
-      return field.staticValue;
+      return field.staticValue as Instance;
     }
 
     var r1Ref = await valueOfField('r1');
diff --git a/runtime/observatory/tests/service/typed_data_test.dart b/runtime/observatory/tests/service/typed_data_test.dart
index 7c34f32..13dd5ee 100644
--- a/runtime/observatory/tests/service/typed_data_test.dart
+++ b/runtime/observatory/tests/service/typed_data_test.dart
@@ -90,7 +90,7 @@
 
     expectTypedData(name, expectedValue) {
       var variable = lib.variables.singleWhere((v) => v.name == name);
-      var actualValue = variable.staticValue.typedElements;
+      var actualValue = (variable.staticValue as Instance).typedElements;
       if (expectedValue is Int32x4List) {
         expect(actualValue.length, equals(expectedValue.length));
         for (var i = 0; i < actualValue.length; i++) {