Support for extending native classes

sdk/lib/_internal/compiler/implementation/elements/elements.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 elements;
 
 
 import '../tree/tree.dart';
 import '../util/util.dart';
 import '../resolution/resolution.dart';
@@ skipping 314 matching lines @@
     return isStaticOrTopLevel(element)
            && (identical(element.kind, ElementKind.FUNCTION));
   }
 
   static bool isInstanceMethod(Element element) {
     return !Elements.isUnresolved(element)
            && element.isInstanceMember()
            && (identical(element.kind, ElementKind.FUNCTION));
   }
 
+  static bool isNativeOrExtendsNative(ClassElement element) {
+    if (element == null) return false;
+    if (element.isNative()) return true;
+    return isNativeOrExtendsNative(element.superclass);
+  }
+
   static bool isInstanceSend(Send send, TreeElements elements) {
     Element element = elements[send];
     if (element == null) return !isClosureSend(send, element);
     return isInstanceMethod(element) || isInstanceField(element);
   }
 
   static bool isClosureSend(Send send, Element element) {
     if (send.isPropertyAccess) return false;
     if (send.receiver != null) return false;
     Node selector = send.selector;
     // this().
     if (selector.isThis()) return true;
     // (o)() or foo()().
     if (element == null && selector.asIdentifier() == null) return true;
     if (element == null) return false;
     // foo() with foo a local or a parameter.
     return isLocal(element);
   }
 
   static SourceString reconstructConstructorNameSourceString(Element element) {
     if (element.name == const SourceString('')) {
       return element.getEnclosingClass().name;
     } else {
       return new SourceString(reconstructConstructorName(element));
     }
   }
-  
+
   // TODO(johnniwinther): Remove this method.
   static String reconstructConstructorName(Element element) {
     String className = element.getEnclosingClass().name.slowToString();
     if (element.name == const SourceString('')) {
       return className;
     } else {
       return '$className\$${element.name.slowToString()}';
     }
   }
 
@@ skipping 565 matching lines @@
   int get resolutionState;
   Token get beginToken;
   Token get endToken;
 
   // TODO(kasperl): Try to get rid of these.
   void set annotatedElement(Element value);
   void set resolutionState(int value);
 
   MetadataAnnotation ensureResolved(Compiler compiler);
 }