Support for extending native classes

sdk/lib/_internal/compiler/implementation/js_backend/namer.dart

 // Copyright (c) 2011, 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.
 
 part of js_backend;
 
 /**
  * Assigns JavaScript identifiers to Dart variables, class-names and members.
  */
 class Namer implements ClosureNamer {
@@ skipping 551 matching lines @@
       if (cls == backend.jsArrayClass) return "a";
       if (cls == backend.jsDoubleClass) return "d";
       if (cls == backend.jsIntClass) return "i";
       if (cls == backend.jsNumberClass) return "n";
       if (cls == backend.jsNullClass) return "u";
       if (cls == backend.jsBoolClass) return "b";
       if (cls == backend.jsInterceptorClass) return "I";
       return cls.name.slowToString();
     }
     List<String> names = classes
-        .where((cls) => !cls.isNative())
+        .where((cls) => !Elements.isNativeOrExtendsNative(cls))
         .map(abbreviate)
         .toList();
     // There is one dispatch mechanism for all native classes.
-    if (classes.any((cls) => cls.isNative())) {
+    if (classes.any((cls) => Elements.isNativeOrExtendsNative(cls))) {
       names.add("x");
     }
     // Sort the names of the classes after abbreviating them to ensure
     // the suffix is stable and predictable for the suggested names.
     names.sort();
     return names.join();
   }
 
   String getInterceptorName(Element element, Iterable<ClassElement> classes) {
     JavaScriptBackend backend = compiler.backend;
@@ skipping 680 matching lines @@
         if (!first) {
           sb.write('_');
         }
         sb.write('_');
         visit(link.head);
         first = true;
       }
     }
   }
 }