Fix various parser bugs related to modifiers of top-level and class members.

dart/sdk/lib/_internal/lib/js_mirrors.dart

 // Copyright (c) 2013, 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 dart._js_mirrors;
 
 import 'dart:async';
 import 'dart:collection' show UnmodifiableListView;
 import 'dart:mirrors';
 
@@ skipping 86 matching lines @@
           new JsLibraryMirror(
               s(name), uri, classes, functions, metadata, fields, isRoot));
     }
     return result;
   }
 }
 
 abstract class JsMirror implements Mirror {
   const JsMirror();
 
-  abstract String get _prettyName;
+  String get _prettyName;
 
   String toString() => _prettyName;
 
   // TODO(ahe): Remove this method from the API.
   MirrorSystem get mirrors => currentJsMirrorSystem;
 
   _getField(JsMirror receiver) {
     throw new UnimplementedError();
   }
 
@@ skipping 1401 matching lines @@
   void operator []=(K key, V value) => _throw();
 
   V putIfAbsent(K key, V ifAbsent()) { _throw(); }
 
   void addAll(Map<K, V> other) => _throw();
 
   V remove(K key) { _throw(); }
 
   void clear() => _throw();
 }