Add ElementCodegenWorldBuilder

tests/compiler/dart2js/compiler_helper.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.
 
 library compiler_helper;
 
 import 'dart:async';
 import "package:expect/expect.dart";
 
 import 'package:compiler/compiler_new.dart';
 
 import 'package:compiler/src/elements/elements.dart';
 export 'package:compiler/src/elements/elements.dart';
 
 import 'package:compiler/src/js_backend/js_backend.dart' as js;
+import 'package:compiler/src/js_backend/element_strategy.dart'
+    show ElementCodegenWorkItem;
 
 import 'package:compiler/src/commandline_options.dart';
 import 'package:compiler/src/common/codegen.dart';
 import 'package:compiler/src/common/resolution.dart';
 
 export 'package:compiler/src/diagnostics/messages.dart';
 export 'package:compiler/src/diagnostics/source_span.dart';
 export 'package:compiler/src/diagnostics/spannable.dart';
 
 export 'package:compiler/src/types/types.dart' show TypeMask;
@@ skipping 50 matching lines @@
     MethodElement element = mainApp.find(entry);
     if (element == null) return null;
     compiler.phase = Compiler.PHASE_RESOLVING;
     compiler.processQueue(compiler.enqueuer.resolution, element,
         compiler.libraryLoader.libraries);
     ResolutionWorkItem resolutionWork =
         new ResolutionWorkItem(compiler.resolution, element);
     resolutionWork.run();
     ClosedWorld closedWorld = compiler.closeResolution().closedWorld;
     CodegenWorkItem work =
-        new CodegenWorkItem(compiler.backend, closedWorld, element);
+        new ElementCodegenWorkItem(compiler.backend, closedWorld, element);
     compiler.phase = Compiler.PHASE_COMPILING;
     work.run();
     js.JavaScriptBackend backend = compiler.backend;
     String generated = backend.getGeneratedCode(element);
     if (check != null) {
       check(generated);
     }
     return returnAll ? outputCollector.getOutput('', OutputType.js) : generated;
   } else {
     List<String> options = <String>[Flags.disableTypeInference];
@@ skipping 199 matching lines @@
     }
   }
 
   return checker;
 }
 
 RegExp _directivePattern = new RegExp(
     //      \1                     \2        \3
     r'''// *(present|absent): *(?:"([^"]*)"|'([^'']*)')''',
     multiLine: true);