Refactor Parsing to remove compiler dependency

tests/compiler/dart2js/find_my_name_test.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 "package:expect/expect.dart";
 import "package:async_helper/async_helper.dart";
 import "package:compiler/src/elements/elements.dart";
 import "mock_compiler.dart";
 import "parser_helper.dart";
 import 'package:compiler/src/elements/modelx.dart';
@@ skipping 18 matching lines @@
 main() {
   asyncTest(() => MockCompiler.create((MockCompiler compiler) {
     testClass(TEST_0, compiler);
     testClass(TEST_1, compiler);
   }));
 }
 
 testClass(String code, MockCompiler compiler) {
   int skip = code.indexOf('{');
   ClassElementX cls = parseUnit(code, compiler, compiler.mainApp).head;
-  cls.parseNode(compiler.parsing);
+  cls.parseNode(compiler.parsingContext);
   cls.forEachLocalMember((Element e) {
     String name = e.name;
     if (e.isConstructor) {
       name = Elements.reconstructConstructorName(e).replaceFirst(r'$', '.');
     }
     Expect.equals(code.indexOf(name, skip), e.position.charOffset);
   });
 }