Issue 3931. Visit children nodes safely.

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

Index: compiler/java/com/google/dart/compiler/ast/DartFieldDefinition.java
diff --git a/compiler/java/com/google/dart/compiler/ast/DartFieldDefinition.java b/compiler/java/com/google/dart/compiler/ast/DartFieldDefinition.java
index 3425189d0f1f3a1ba9a228f1dea0d70d6200d527..b698efc00438e6d401645187dcb6baf51095f48a 100644
--- a/compiler/java/com/google/dart/compiler/ast/DartFieldDefinition.java
+++ b/compiler/java/com/google/dart/compiler/ast/DartFieldDefinition.java
@@ -1,4 +1,4 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
@@ -33,9 +33,7 @@ public class DartFieldDefinition extends DartNode {
 
   @Override
   public void visitChildren(ASTVisitor<?> visitor) {
-    if (getTypeNode() != null) {
-      getTypeNode().accept(visitor);
-    }
+    safelyVisitChild(typeNode, visitor);
     fields.accept(visitor);
   }