Add @JSName annotation for native fields and methods.

sdk/lib/_internal/compiler/implementation/scanner/listener.dart

Index: sdk/lib/_internal/compiler/implementation/scanner/listener.dart
diff --git a/sdk/lib/_internal/compiler/implementation/scanner/listener.dart b/sdk/lib/_internal/compiler/implementation/scanner/listener.dart
index e8a15aa55ec01b7b5cc34e3ef5487a1c173f47f6..8dd1a3e07e1b26cb28234a8d150464894b5d7671 100644
--- a/sdk/lib/_internal/compiler/implementation/scanner/listener.dart
+++ b/sdk/lib/_internal/compiler/implementation/scanner/listener.dart
@@ -747,7 +747,7 @@ class ElementListener extends Listener {
   void endClassDeclaration(int interfacesCount, Token beginToken,
                            Token extendsKeyword, Token implementsKeyword,
                            Token endToken) {
-    SourceString nativeName = native.checkForNativeClass(this);
+    SourceString nativeTagInfo = native.checkForNativeClass(this);
     NodeList interfaces =
         makeNodeList(interfacesCount, implementsKeyword, null, ",");
     TypeAnnotation supertype = popNode();
@@ -756,7 +756,7 @@ class ElementListener extends Listener {
     int id = idGenerator();
     ClassElement element = new PartialClassElement(
         name.source, beginToken, endToken, compilationUnitElement, id);
-    element.nativeName = nativeName;
+    element.nativeTagInfo = nativeTagInfo;
     pushElement(element);
     rejectBuiltInIdentifier(name);
   }