Reverting a performance optimization - I'm not comfortable it's side-effect free.

compiler/java/com/google/dart/compiler/ast/DartNode.java

 // 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.
 
 package com.google.dart.compiler.ast;
 
 import com.google.dart.compiler.common.AbstractNode;
 import com.google.dart.compiler.resolver.Element;
 import com.google.dart.compiler.type.Type;
 import com.google.dart.compiler.util.DefaultTextOutput;
@@ skipping 99 matching lines @@
     return super.toString();
   }
 
   /**
    * If the given child is not <code>null</code>, use the given visitor to visit it.
    * 
    * @param child the child to be visited
    * @param visitor the visitor that will be used to visit the child
    */
   protected void safelyVisitChild(DartNode child, ASTVisitor<?> visitor) {
-    // Inline the DartIdentifier path - it's by far the most common.
-    if (child instanceof DartIdentifier) {
-      visitor.visitIdentifier((DartIdentifier)child);
-    } else if (child != null) {
+    if (child != null) {
       child.accept(visitor);
     }
   }
   
 }