Start allowing mixin application extensions.

sdk/lib/_internal/compiler/implementation/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;
 
 /**
  * An event generating parser of Dart programs. This parser expects
  * all tokens in a linked list (aka a token stream).
  *
@@ skipping 466 matching lines @@
       listener.handleModifier(token);
       modifierCount++;
       token = token.next;
     }
     listener.handleModifiers(modifierCount);
     token = parseIdentifier(token.next);
     token = parseTypeVariablesOpt(token);
     Token extendsKeyword;
     if (optional('extends', token)) {
       extendsKeyword = token;
-      token = parseType(token.next);
+      if (optional('with', token.next.next)) {
+        // TODO(kasperl): Disallow modifiers here.
+        token = parseMixinApplication(token.next);
+      } else {
+        token = parseType(token.next);
+      }
     } else {
       extendsKeyword = null;
       listener.handleNoType(token);
     }
     Token implementsKeyword;
     int interfacesCount = 0;
     if (optional('implements', token)) {
       implementsKeyword = token;
       do {
         token = parseType(token.next);
@@ skipping 1689 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }