Issue 3931. Visit children nodes safely.

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

Index: compiler/java/com/google/dart/compiler/ast/DartMapLiteralEntry.java
diff --git a/compiler/java/com/google/dart/compiler/ast/DartMapLiteralEntry.java b/compiler/java/com/google/dart/compiler/ast/DartMapLiteralEntry.java
index fc0b86b5fb9f5f95b7c8541d2f184af43376c67f..f7ced3804436427c90380c3b456a9cfdb01c5c8e 100644
--- a/compiler/java/com/google/dart/compiler/ast/DartMapLiteralEntry.java
+++ b/compiler/java/com/google/dart/compiler/ast/DartMapLiteralEntry.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.
 
@@ -27,8 +27,8 @@ public class DartMapLiteralEntry extends DartNode {
 
   @Override
   public void visitChildren(ASTVisitor<?> visitor) {
-    key.accept(visitor);
-    value.accept(visitor);
+    safelyVisitChild(key, visitor);
+    safelyVisitChild(value, visitor);
   }
 
   @Override