Handle unexpected tokens in modifier lists.

pkg/compiler/lib/src/scanner/parser.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;
 
 class FormalParameterType {
   final String type;
   const FormalParameterType(this.type);
   bool get isRequired => this == REQUIRED;
@@ skipping 1055 matching lines @@
   }
 
   void parseModifierList(Link<Token> tokens) {
     int count = 0;
     for (; !tokens.isEmpty; tokens = tokens.tail) {
       Token token = tokens.head;
       if (isModifier(token)) {
         parseModifier(token);
       } else {
         listener.unexpected(token);
+        // Skip the remaining modifiers.
+        break;
       }
       count++;
     }
     listener.handleModifiers(count);
   }
 
   Token parseModifiers(Token token) {
     int count = 0;
     while (identical(token.kind, KEYWORD_TOKEN)) {
       if (!isModifier(token))
@@ skipping 1575 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }