All strong mode cleaning of dart2js.

pkg/compiler/lib/src/js_emitter/full_emitter/emitter.dart

Index: pkg/compiler/lib/src/js_emitter/full_emitter/emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/full_emitter/emitter.dart b/pkg/compiler/lib/src/js_emitter/full_emitter/emitter.dart
index 702f2f8d6a114f4e7b65d699ed372137dc14bdca..4633fb265cebba88f42b4b66034e4e198efeb031 100644
--- a/pkg/compiler/lib/src/js_emitter/full_emitter/emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/full_emitter/emitter.dart
@@ -19,12 +19,7 @@ import '../../common_elements.dart' show CommonElements, ElementEnvironment;
 import '../../elements/resolution_types.dart' show ResolutionDartType;
 import '../../deferred_load.dart' show OutputUnit;
 import '../../elements/elements.dart'
-    show
-        ClassElement,
-        ConstructorBodyElement,
-        FieldElement,
-        LibraryElement,
-        TypedefElement;
+    show ConstructorBodyElement, FieldElement, LibraryElement, TypedefElement;
 import '../../elements/entities.dart';
 import '../../elements/entity_utils.dart' as utils;
 import '../../elements/names.dart';
@@ -320,7 +315,7 @@ class Emitter extends js_emitter.EmitterBase {
 
   @override
   jsAst.PropertyAccess prototypeAccess(
-      ClassElement element, bool hasBeenInstantiated) {
+      ClassEntity element, bool hasBeenInstantiated) {
     return jsAst.js('#.prototype', constructorAccess(element));
   }