Support class and typedef literals as expressions.

tests/compiler/dart2js/mock_compiler.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 mock_compiler;
 
 import 'dart:uri';
 
 import '../../../lib/compiler/compiler.dart' as api;
 import '../../../lib/compiler/implementation/dart2jslib.dart' hide TreeElementMapping;
@@ skipping 45 matching lines @@
   hasNext(receiver) {}''';
 
 const String DEFAULT_CORELIB = r'''
   print(var obj) {}
   abstract class num {}
   abstract class int extends num { }
   abstract class double extends num { }
   class bool {}
   class String {}
   class Object {}
+  class Type {}
   class Function {}
   interface List default ListImplementation { List([length]);}
   class ListImplementation { factory List([length]) => null; }
   abstract class Map {}
   class Closure {}
   class Null {}
   class Dynamic_ {}
   bool identical(Object a, Object b) {}''';
 
 class MockCompiler extends Compiler {
@@ skipping 176 matching lines @@
   operator []=(Node node, Element element) {
     map[node] = element;
   }
 
   operator [](Node node) => map[node];
 
   void remove(Node node) {
     map.remove(node);
   }
 }