Add NativeEnqueuer to work with the Enqueuer.

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

Index: sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart b/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
index 9cedefbb8a1b1c37d2a730f660ab7ceaa57872b8..a4cfe81987d8e496ab4aecc2ea275b301c138e74 100644
--- a/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
@@ -748,10 +748,17 @@ class JavaScriptBackend extends Backend {
     invalidateAfterCodegen.clear();
   }
 
-  void processNativeClasses(Enqueuer world,
-                            Collection<LibraryElement> libraries) {
-    native.processNativeClasses(world, emitter, libraries);
-  }
+
+  native.NativeEnqueuer nativeResolutionEnqueuer(Enqueuer world) =>
+      new native.NativeResolutionEnqueuer(world, compiler);
+
+  native.NativeEnqueuer nativeCodegenEnqueuer(Enqueuer world) =>
+      new native.NativeCodegenEnqueuer(world, compiler, emitter);
+
+  //void processNativeClasses(Enqueuer world,
+  //                          Collection<LibraryElement> libraries) {
+  //  native.processNativeClasses(world, emitter, libraries);
+  //}
 
   void assembleProgram() {
     emitter.assembleProgram();