dart2js cps: Use dummy constant in dummy receiver optimization.

pkg/compiler/lib/src/js_backend/codegen/glue.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 code_generator_dependencies;
 
 import '../js_backend.dart';
 import '../../common/registry.dart' show
     Registry;
 import '../../compiler.dart' show
@@ skipping 36 matching lines @@
   ClassWorld get classWorld => _compiler.world;
 
   js.Expression constantReference(ConstantValue value) {
     return _emitter.constantReference(value);
   }
 
   reportInternalError(String message) {
     _compiler.internalError(_compiler.currentElement, message);
   }
 
-  bool isUsedAsMixin(ClassElement clazz) {
-    return classWorld.isUsedAsMixin(clazz);
+  bool isUsedAsMixin(ClassElement classElement) {
+    return classWorld.isUsedAsMixin(classElement);
   }
 
   ConstantValue getConstantValueForVariable(VariableElement variable) {
     return _backend.constants.getConstantValueForVariable(variable);
   }
 
   js.Expression staticFunctionAccess(FunctionElement element) {
     return _backend.emitter.staticFunctionAccess(element);
   }
 
@@ skipping 193 matching lines @@
   ClassElement get jsMutableArrayClass => _backend.jsMutableArrayClass;
 
   bool isStringClass(ClassElement classElement) =>
       classElement == _backend.jsStringClass ||
       classElement == _compiler.stringClass;
 
   bool isBoolClass(ClassElement classElement) =>
       classElement == _backend.jsBoolClass ||
       classElement == _compiler.boolClass;
 }