Issue 3931. Visit children nodes safely.

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

Index: compiler/java/com/google/dart/compiler/ast/DartForInStatement.java
diff --git a/compiler/java/com/google/dart/compiler/ast/DartForInStatement.java b/compiler/java/com/google/dart/compiler/ast/DartForInStatement.java
index 369f819893618d33111bc3a407a8c73d96331a11..86b8e177402fc4d037e78c89657b690d8f1c5b5e 100644
--- a/compiler/java/com/google/dart/compiler/ast/DartForInStatement.java
+++ b/compiler/java/com/google/dart/compiler/ast/DartForInStatement.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.
 
@@ -45,9 +45,9 @@ public class DartForInStatement extends DartStatement {
 
   @Override
   public void visitChildren(ASTVisitor<?> visitor) {
-    setup.accept(visitor);
-    iterable.accept(visitor);
-    body.accept(visitor);
+    safelyVisitChild(setup, visitor);
+    safelyVisitChild(iterable, visitor);
+    safelyVisitChild(body, visitor);
   }
 
   @Override