Disable implicit casts (dart-lang/stack_trace#61)

diff --git a/pkgs/stack_trace/analysis_options.yaml b/pkgs/stack_trace/analysis_options.yaml
index 7472eb0..3384ee6 100644
--- a/pkgs/stack_trace/analysis_options.yaml
+++ b/pkgs/stack_trace/analysis_options.yaml

@@ -1,3 +1,6 @@
+analyzer:
+  strong-mode:
+    implicit-casts: false
 linter:
   rules:
     - prefer_equal_for_default_values

diff --git a/pkgs/stack_trace/lib/src/chain.dart b/pkgs/stack_trace/lib/src/chain.dart
index da6fb6f..3397f34 100644
--- a/pkgs/stack_trace/lib/src/chain.dart
+++ b/pkgs/stack_trace/lib/src/chain.dart

@@ -47,7 +47,8 @@
   final List<Trace> traces;
 
   /// The [StackZoneSpecification] for the current zone.
-  static StackZoneSpecification get _currentSpec => Zone.current[_specKey];
+  static StackZoneSpecification get _currentSpec =>
+      Zone.current[_specKey] as StackZoneSpecification;
 
   /// If [when] is `true`, runs [callback] in a [Zone] in which the current
   /// stack chain is tracked and automatically associated with (most) errors.
@@ -81,7 +82,7 @@
     }
 
     if (!when) {
-      var newOnError;
+      void Function(Object, StackTrace) newOnError;
       if (onError != null) {
         newOnError = (error, stackTrace) {
           onError(

diff --git a/pkgs/stack_trace/lib/src/frame.dart b/pkgs/stack_trace/lib/src/frame.dart
index 752dcb7..ae19182 100644
--- a/pkgs/stack_trace/lib/src/frame.dart
+++ b/pkgs/stack_trace/lib/src/frame.dart

@@ -165,7 +165,7 @@
 
         // v8 location strings can be arbitrarily-nested, since it adds a layer
         // of nesting for each eval performed on that line.
-        parseLocation(location, member) {
+        Frame parseLocation(String location, String member) {
           var evalMatch = _v8EvalLocation.firstMatch(location);
           while (evalMatch != null) {
             location = evalMatch[1];
@@ -240,7 +240,7 @@
         // Normally this is a URI, but in a jsshell trace it can be a path.
         var uri = _uriOrPathToUri(match[3]);
 
-        var member;
+        String member;
         if (match[1] != null) {
           member = match[1];
           member +=

diff --git a/pkgs/stack_trace/lib/src/stack_zone_specification.dart b/pkgs/stack_trace/lib/src/stack_zone_specification.dart
index 4ef4eae..7420e0a 100644
--- a/pkgs/stack_trace/lib/src/stack_zone_specification.dart
+++ b/pkgs/stack_trace/lib/src/stack_zone_specification.dart

@@ -133,7 +133,7 @@
   /// Tracks the current stack chain so it can be set to [_currentChain] when
   /// [f] is run.
   ZoneBinaryCallback<R, T1, T2> _registerBinaryCallback<R, T1, T2>(
-      Zone self, ZoneDelegate parent, Zone zone, Function f) {
+      Zone self, ZoneDelegate parent, Zone zone, R Function(T1, T2) f) {
     if (f == null || _disabled) return parent.registerBinaryCallback(zone, f);
 
     var node = _createNode(1);

diff --git a/pkgs/stack_trace/test/chain/dart2js_test.dart b/pkgs/stack_trace/test/chain/dart2js_test.dart
index fbbad56..827c459 100644
--- a/pkgs/stack_trace/test/chain/dart2js_test.dart
+++ b/pkgs/stack_trace/test/chain/dart2js_test.dart

@@ -305,7 +305,7 @@
     test(
         'called for an unregistered stack trace returns a chain wrapping that '
         'trace', () {
-      var trace;
+      StackTrace trace;
       var chain = Chain.capture(() {
         try {
           throw 'error';
@@ -324,7 +324,7 @@
   test(
       'forTrace() outside of capture() returns a chain wrapping the given '
       'trace', () {
-    var trace;
+    StackTrace trace;
     var chain = Chain.capture(() {
       try {
         throw 'error';

diff --git a/pkgs/stack_trace/test/chain/utils.dart b/pkgs/stack_trace/test/chain/utils.dart
index c1f98e4..790693a 100644
--- a/pkgs/stack_trace/test/chain/utils.dart
+++ b/pkgs/stack_trace/test/chain/utils.dart

@@ -74,7 +74,7 @@
   });
 
   return completer.future
-      .catchError((_, stackTrace) => Chain.forTrace(stackTrace));
+      .catchError((_, StackTrace stackTrace) => Chain.forTrace(stackTrace));
 }
 
 /// Runs [callback] in a [Chain.capture] zone and returns a Future that

diff --git a/pkgs/stack_trace/test/chain/vm_test.dart b/pkgs/stack_trace/test/chain/vm_test.dart
index c006d88..842f0a0 100644
--- a/pkgs/stack_trace/test/chain/vm_test.dart
+++ b/pkgs/stack_trace/test/chain/vm_test.dart

@@ -481,7 +481,7 @@
       'chain', () {
     // Disable the test package's chain-tracking.
     return Chain.disable(() async {
-      var trace;
+      StackTrace trace;
       await Chain.capture(() async {
         try {
           throw 'error';