Fix 2 host-checked error with the enqueuer:

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.
 // Test constant folding.
 
 library compiler_helper;
 
 import "package:expect/expect.dart";
 
 import '../../../sdk/lib/_internal/compiler/implementation/elements/elements.dart'
@@ skipping 53 matching lines @@
   compiler.phase = Compiler.PHASE_RESOLVING;
   compiler.backend.enqueueHelpers(compiler.enqueuer.resolution,
                                   compiler.globalDependencies);
   compiler.processQueue(compiler.enqueuer.resolution, element);
   compiler.world.populate();
   var context = new js.JavaScriptItemCompilationContext();
   leg.ResolutionWorkItem resolutionWork =
       new leg.ResolutionWorkItem(element, context);
   resolutionWork.run(compiler, compiler.enqueuer.resolution);
   leg.CodegenWorkItem work =
-      new leg.CodegenWorkItem(element, resolutionWork.resolutionTree, context);
+      new leg.CodegenWorkItem(element, context);
   compiler.phase = Compiler.PHASE_COMPILING;
   work.run(compiler, compiler.enqueuer.codegen);
   js.JavaScriptBackend backend = compiler.backend;
   return backend.assembleCode(element);
 }
 
 MockCompiler compilerFor(String code, Uri uri,
                          {bool analyzeAll: false,
                           bool analyzeOnly: false,
                           String coreSource: DEFAULT_CORELIB}) {
@@ skipping 124 matching lines @@
   final xRe = new RegExp('\\bx\\b');
   regexp = regexp.replaceAll(xRe, '(?:$anyIdentifier)');
   final spaceRe = new RegExp('\\s+');
   regexp = regexp.replaceAll(spaceRe, '(?:\\s*)');
   if (shouldMatch) {
     Expect.isTrue(new RegExp(regexp).hasMatch(generated));
   } else {
     Expect.isFalse(new RegExp(regexp).hasMatch(generated));
   }
 }