dart2js: Fix types in new emitter.

pkg/compiler/lib/src/js_emitter/model.dart

 // Copyright (c) 2014, 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.
 
 library dart2js.new_js_emitter.model;
 
 import '../js/js.dart' as js show Expression;
 import '../constants/values.dart' show ConstantValue;
 
 import '../deferred_load.dart' show OutputUnit;
@@ skipping 349 matching lines @@
  * A method that is generated by the backend and has not direct correspondence
  * to a method in the original Dart program. Examples are getter and setter
  * stubs and stubs to dispatch calls to methods with optional parameters.
  */
 class StubMethod extends Method {
   StubMethod(String name, js.Expression code,
              {Element element})
       : super(element, name, code);
 }
 
-class StaticMethod extends DartMethod {
+abstract class StaticMethod implements Method {
+  Holder get holder;
+}
+
+class StaticDartMethod extends DartMethod implements StaticMethod {
   final Holder holder;
-  StaticMethod(Element element, String name, this.holder, js.Expression code,
-               {bool needsTearOff, String tearOffName, bool canBeApplied,
-                bool canBeReflected, bool needsStubs})
+
+  StaticDartMethod(Element element, String name, this.holder,
+                   js.Expression code,
+                   {bool needsTearOff, String tearOffName, bool canBeApplied,
+                    bool canBeReflected, bool needsStubs})
       : super(element, name, code,
               needsTearOff: needsTearOff,
               tearOffName : tearOffName,
               canBeApplied : canBeApplied,
               canBeReflected : canBeReflected,
               needsStubs : needsStubs);
 }
 
-class StaticStubMethod extends StubMethod {
+class StaticStubMethod extends StubMethod implements StaticMethod {
   Holder holder;
   StaticStubMethod(String name, this.holder, js.Expression code)
       : super(name, code);
 }