Use entities in code_emitter_task

pkg/compiler/lib/src/js_backend/constant_emitter.dart

 // Copyright (c) 2012, 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.
 
 import '../common.dart';
 import '../compiler.dart' show Compiler;
 import '../constants/values.dart';
 import '../elements/resolution_types.dart';
 import '../elements/elements.dart';
 import '../io/code_output.dart';
@@ skipping 245 matching lines @@
     }
 
     jsAst.Expression constructor =
         backend.emitter.constructorAccess(classElement);
     jsAst.Expression value = new jsAst.New(constructor, arguments);
     return value;
   }
 
   JavaScriptBackend get backend => compiler.backend;
 
-  jsAst.PropertyAccess getHelperProperty(Element helper) {
+  jsAst.PropertyAccess getHelperProperty(MethodElement helper) {
     return backend.emitter.staticFunctionAccess(helper);
   }
 
   @override
   jsAst.Expression visitType(TypeConstantValue constant, [_]) {
     ResolutionDartType type = constant.representedType;
     jsAst.Name typeName = namer.runtimeTypeName(type.element);
     return new jsAst.Call(getHelperProperty(backend.helpers.createRuntimeType),
         [js.quoteName(typeName)]);
   }
@@ skipping 72 matching lines @@
       arguments.add(rtiEncoder.getTypeRepresentation(argument, unexpected));
     }
     return new jsAst.ArrayInitializer(arguments);
   }
 
   @override
   jsAst.Expression visitDeferred(DeferredConstantValue constant, [_]) {
     return constantReferenceGenerator(constant.referenced);
   }
 }