Refactor Library/CompilationUnit and how we define local Scope.

tests/compiler/dart2js/parser_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('parser_helper');
 
 #import("dart:uri");
 
 #import("../../../lib/compiler/implementation/elements/elements.dart");
 #import("../../../lib/compiler/implementation/tree/tree.dart");
@@ skipping 54 matching lines @@
 Link<Element> parseUnit(String text, Compiler compiler,
                         LibraryElement library) {
   Token tokens = scan(text);
   Uri uri = new Uri.fromComponents(scheme: "source");
   var script = new Script(uri, new MockFile(text));
   var unit = new CompilationUnitElement(script, library);
   int id = 0;
   ElementListener listener = new ElementListener(compiler, unit, () => id++);
   PartialParser parser = new PartialParser(listener);
   compiler.withCurrentElement(unit, () => parser.parseUnit(tokens));
-  return unit.topLevelElements;
+  return unit.localMembers;
 }
 
 // TODO(ahe): We define this method to avoid having to import
 // the scanner in the tests. We should move SourceString to another
 // location instead.
 SourceString buildSourceString(String name) {
   return new SourceString(name);
 }