Use entities in class_stub_generator.

pkg/compiler/lib/src/js_emitter/native_emitter.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.js_emitter.native_emitter;
 
 import '../common.dart';
 import '../compiler.dart' show Compiler;
 import '../elements/resolution_types.dart'
-    show
-    ResolutionDartType,
-    ResolutionFunctionType;
+    show ResolutionDartType, ResolutionFunctionType;
 import '../elements/elements.dart'
     show
-    ClassElement,
-    Element,
-    FunctionElement,
-    FunctionSignature,
-    ParameterElement;
+        ClassElement,
+        Element,
+        FunctionElement,
+        FunctionSignature,
+        ParameterElement;
 import '../js/js.dart' as jsAst;
 import '../js/js.dart' show js;
 import '../js_backend/backend_helpers.dart' show BackendHelpers;
-import '../js_backend/js_backend.dart'
-    show
-    JavaScriptBackend;
+import '../js_backend/js_backend.dart' show JavaScriptBackend;
 import 'full_emitter/emitter.dart' as full_js_emitter;
 
 import 'code_emitter_task.dart' show CodeEmitterTask;
 import 'model.dart';
 
 class NativeEmitter {
   // TODO(floitsch): the native-emitter should not know about ClassBuilders.
   final Map<Element, full_js_emitter.ClassBuilder> cachedBuilders;
 
   final CodeEmitterTask emitterTask;
@@ skipping 338 matching lines @@
     // used.  We should also use an interceptor if the check can't be satisfied
     // by a native class in case we get a native instance that tries to spoof
     // the type info.  i.e the criteria for whether or not to use an interceptor
     // is whether the receiver can be native, not the type of the test.
     if (element == null || !element.isClass) return false;
     ClassElement cls = element;
     if (backend.isNativeOrExtendsNative(cls)) return true;
     return isSupertypeOfNativeClass(element);
   }
 }