Make patching of classes lazy.

tests/compiler/dart2js/patch_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("../../../lib/compiler/implementation/leg.dart");
 #import("../../../lib/compiler/implementation/elements/elements.dart");
 #import("../../../lib/compiler/implementation/tree/tree.dart");
 #import("../../../lib/compiler/implementation/util/util.dart");
 #import("mock_compiler.dart");
 #import("parser_helper.dart");
 #import("dart:uri");
 
 Compiler applyPatch(String script, String patch) {
   String core = "$DEFAULT_CORELIB\n$script";
   MockCompiler compiler = new MockCompiler(coreSource: core);
   var uri = new Uri("core.dartp");
   compiler.sourceFiles[uri.toString()] = new MockFile(patch);
   compiler.patchParser.patchLibrary(uri, compiler.coreLibrary);
-  compiler.applyClassPatches(compiler.coreLibrary);
   return compiler;
 }
 
 Element ensure(compiler,
                String name,
                Element lookup(name),
                [bool isPatched = true,
                 bool hasBody = false,
                 bool isGetter = false]) {
   var element = lookup(buildSourceString(name));
@@ skipping 29 matching lines @@
       class Class {
         external String toString();
       }
       """,
       """
       patch class Class {
         patch String toString() => 'string';
       }
       """);
   var container = ensure(compiler, "Class", compiler.coreLibrary.find);
+  container.parseNode(compiler);
   ensure(compiler, "toString", container.lookupLocalMember, hasBody:true);
 }
 
 testPatchGetter() {
   var compiler = applyPatch(
       """
       class Class {
         external int get field();
       }
       """,
       """
       patch class Class {
         patch int get field() => 5;
       }
       """);
   var container = ensure(compiler, "Class", compiler.coreLibrary.find);
+  container.parseNode(compiler);
   ensure(compiler,
          "field",
          container.lookupLocalMember,
          isGetter: true,
          hasBody: true);
 }
 
 testInjectFunction() {
   var compiler = applyPatch(
       "",
       "int _function() => 5;");
   ensure(compiler,
          "_function",
          compiler.coreLibrary.find,
          hasBody: true,
          isPatched: false);
 }
 
 main() {
   testPatchFunction();
   testPatchMember();
   testPatchGetter();
   testInjectFunction();
 }