Add @JSName annotation for native fields and methods.

sdk/lib/_internal/compiler/implementation/enqueue.dart

Index: sdk/lib/_internal/compiler/implementation/enqueue.dart
diff --git a/sdk/lib/_internal/compiler/implementation/enqueue.dart b/sdk/lib/_internal/compiler/implementation/enqueue.dart
index 111358d7507d378474ce2de88ef9a2346c04c798..7a049c3a2bb41ced342668d373e6ae3baa23edf0 100644
--- a/sdk/lib/_internal/compiler/implementation/enqueue.dart
+++ b/sdk/lib/_internal/compiler/implementation/enqueue.dart
@@ -210,6 +210,7 @@ class Enqueuer {
       }
     } else if (member.kind == ElementKind.FIELD &&
                member.enclosingElement.isNative()) {
+      nativeEnqueuer.registerField(member);
       if (universe.hasInvokedGetter(member, compiler) ||
           universe.hasInvocation(member, compiler)) {
         nativeEnqueuer.registerFieldLoad(member);