Handle named and optional arguments in cps-ir.

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 '../../dart2jslib.dart';
 import '../../js_emitter/js_emitter.dart';
 import '../../js/js.dart' as js;
 import '../../constants/values.dart';
 import '../../elements/elements.dart';
+import '../../constants/expressions.dart';
 
 /// Encapsulates the dependencies of the function-compiler to the compiler,
 /// backend and emitter.
 // TODO(sigurdm): Should be refactored when we have a better feeling for the
 // interface.
 class Glue {
   final Compiler _compiler;
 
   JavaScriptBackend get _backend => _compiler.backend;
   CodeEmitterTask get _emitter => _backend.emitter;
   Namer get _namer => _backend.namer;
 
   Glue(this._compiler);
 
   js.Expression constantReference(ConstantValue value) {
     return _emitter.constantReference(value);
   }
 
+  ConstantExpression getConstantForVariable(VariableElement variable) {
+    return _backend.constants.getConstantForVariable(variable);
+  }
+
   js.Expression elementAccess(Element element) {
     return _namer.elementAccess(element);
   }
 
   String safeVariableName(String name) {
     return _namer.safeVariableName(name);
   }
 
 }