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

dart/sdk/lib/_internal/compiler/implementation/scanner/listener.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.
 
 part of scanner;
 
 const bool VERBOSE = false;
 
 /**
  * A parser event listener that does nothing except throw exceptions
@@ skipping 577 matching lines @@
   void recoverableError(String message, {Token token, Node node}) {
     if (token == null && node != null) {
       token = node.getBeginToken();
     }
     error(message, token);
   }
 
   void error(String message, Token token) {
     throw new ParserError("$message @ ${token.charOffset}");
   }
+
+  void reportError(Spannable spannable,
+                   MessageKind errorCode,
+                   [Map arguments = const {}]) {
+    String message = errorCode.error(arguments, true).toString();
+    Token token;
+    Node node;
+    if (spannable is Token) {
+      token = spannable;
+    } else if (spannable is Node) {
+      node = spannable;
+    } else {
+      throw new ParserError(message);
+    }
+    recoverableError(message, token: token, node: node);
+  }
 }
 
 class ParserError {
   final String reason;
   ParserError(this.reason);
   toString() => reason;
 }
 
 typedef int IdGenerator();
 
@@ skipping 507 matching lines @@
     assert(stringCount != 0);
     Expression accumulator = popNode();
     stringCount--;
     while (stringCount > 0) {
       Expression expression = popNode();
       accumulator = new StringJuxtaposition(expression, accumulator);
       stringCount--;
     }
     pushNode(accumulator);
   }
+
+  void reportError(Spannable spannable,
+                   MessageKind errorCode,
+                   [Map arguments = const {}]) {
+    listener.reportError(spannable, errorCode, arguments);
+  }
 }
 
 class NodeListener extends ElementListener {
   NodeListener(DiagnosticListener listener, CompilationUnitElement element)
     : super(listener, element, null);
 
   void addLibraryTag(LibraryTag tag) {
     pushNode(tag);
   }
 
@@ skipping 840 matching lines @@
 
 Node parse(DiagnosticListener diagnosticListener,
            CompilationUnitElement element,
            doParse(Parser parser)) {
   NodeListener listener = new NodeListener(diagnosticListener, element);
   doParse(new Parser(listener));
   Node node = listener.popNode();
   assert(listener.nodes.isEmpty);
   return node;
 }