dart2js cps: Do not add identical calls for foreign code conditions.

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 '../../constants/values.dart';
 import '../../dart_types.dart' show
     DartType,
@@ skipping 21 matching lines @@
   FunctionElement get getInterceptorMethod => _backend.getInterceptorMethod;
 
   JavaScriptBackend get _backend => _compiler.backend;
 
   CodeEmitterTask get _emitter => _backend.emitter;
 
   Namer get _namer => _backend.namer;
 
   Glue(this._compiler);
 
+  ClassWorld get classWorld => _compiler.world;
+
   js.Expression constantReference(ConstantValue value) {
     return _emitter.constantReference(value);
   }
 
   reportInternalError(String message) {
     _compiler.internalError(_compiler.currentElement, message);
   }
 
   ConstantValue getConstantValueForVariable(VariableElement variable) {
     return _backend.constants.getConstantValueForVariable(variable);
@@ skipping 187 matching lines @@
     return _backend.operatorEqHandlesNullArgument(element);
   }
 
   bool hasStrictSubtype(ClassElement element) {
     return _compiler.world.hasAnyStrictSubtype(element);
   }
 
   ClassElement get jsExtendableArrayClass => _backend.jsExtendableArrayClass;
   ClassElement get jsMutableArrayClass => _backend.jsMutableArrayClass;
 }