checkpoint (#1817)

diff --git a/lib/dartdoc.dart b/lib/dartdoc.dart
index 747b66f..5cd2d80 100644
--- a/lib/dartdoc.dart
+++ b/lib/dartdoc.dart
@@ -12,8 +12,9 @@
 import 'dart:convert';
 import 'dart:io';
 
-import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/dart/analysis/results.dart';
+import 'package:analyzer/error/error.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
diff --git a/lib/src/model.dart b/lib/src/model.dart
index a0204b9..e61e047 100644
--- a/lib/src/model.dart
+++ b/lib/src/model.dart
@@ -11,8 +11,13 @@
 import 'dart:io';
 
 import 'package:analyzer/dart/ast/ast.dart'
-    show Declaration, Expression, InstanceCreationExpression;
-import 'package:analyzer/dart/ast/ast.dart';
+    show
+        AnnotatedNode,
+        AstNode,
+        CommentReference,
+        Declaration,
+        Expression,
+        InstanceCreationExpression;
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/file_system/file_system.dart' as fileSystem;
@@ -489,7 +494,7 @@
 
 /// Implements the Dart 2.1 "mixin" style of mixin declarations.
 class Mixin extends Class {
-  Mixin(MixinElementImpl element, Library library, PackageGraph packageGraph)
+  Mixin(ClassElement element, Library library, PackageGraph packageGraph)
       : super(element, library, packageGraph) {}
 
   @override
@@ -521,7 +526,7 @@
   /// Returns a list of superclass constraints for this mixin.
   Iterable<ParameterizedElementType> get superclassConstraints {
     if (_superclassConstraints == null) {
-      _superclassConstraints = (element as MixinElementImpl)
+      _superclassConstraints = (element as ClassElement)
           .superclassConstraints
           .map<ParameterizedElementType>(
               (InterfaceType i) => new ElementType.from(i, packageGraph))
diff --git a/lib/src/special_elements.dart b/lib/src/special_elements.dart
index b6644bc..9c21139 100644
--- a/lib/src/special_elements.dart
+++ b/lib/src/special_elements.dart
@@ -75,7 +75,7 @@
 ];
 
 /// Given a SDK, resolve URIs for the libraries containing our special
-/// clases.
+/// classes.
 Set<String> specialLibraryFiles(DartSdk sdk) => _specialClassDefinitions
     .map((_SpecialClassDefinition d) => d.getSpecialFilename(sdk))
     .where((String s) => s != null)