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 cf9c8a4ae3c23fc53451f7b1dc623765c7102686..2aa1fc8663ff4baccd70fcdf44705d4ceeaffd57 100644
--- a/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
@@ -811,9 +811,13 @@ class JavaScriptBackend extends Backend {
     invalidateAfterCodegen.clear();
   }
 
-  void processNativeClasses(Enqueuer world,
-                            Collection<LibraryElement> libraries) {
-    native.processNativeClasses(world, emitter, libraries);
+
+  native.NativeEnqueuer nativeResolutionEnqueuer(Enqueuer world) {
+    return new native.NativeResolutionEnqueuer(world, compiler);
+  }
+
+  native.NativeEnqueuer nativeCodegenEnqueuer(Enqueuer world) {
+    return new native.NativeCodegenEnqueuer(world, compiler, emitter);
   }
 
   void assembleProgram() {