Refactor DartTypeVisitor and ElementVisitor.

pkg/compiler/lib/src/scanner/class_element_parser.dart

 // Copyright (c) 2011, 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 ClassElementParser extends PartialParser {
   ClassElementParser(Listener listener) : super(listener);
 
   Token parseClassBody(Token token) => fullParseClassBody(token);
@@ skipping 73 matching lines @@
     });
     return cachedNode;
   }
 
   Token get position => beginToken;
 
   // TODO(johnniwinther): Ensure that modifiers are always available.
   Modifiers get modifiers =>
       cachedNode != null ? cachedNode.modifiers : Modifiers.EMPTY;
 
-  accept(ElementVisitor visitor) => visitor.visitClassElement(this);
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitClassElement(this, arg);
+  }
 
   PartialClassElement copyWithEnclosing(CompilationUnitElement enclosing) {
     return new PartialClassElement(name, beginToken, endToken, enclosing, id);
   }
 }
 
 class MemberListener extends NodeListener {
   final ClassElement enclosingClass;
 
   MemberListener(DiagnosticListener listener,
@@ skipping 135 matching lines @@
 
   void endMetadata(Token beginToken, Token periodBeforeName, Token endToken) {
     popNode(); // Discard arguments.
     if (periodBeforeName != null) {
       popNode(); // Discard name.
     }
     popNode(); // Discard node (Send or Identifier).
     pushMetadata(new PartialMetadataAnnotation(beginToken, endToken));
   }
 }