Issue 3931. Visit children nodes safely.

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

Index: compiler/java/com/google/dart/compiler/ast/DartVariableStatement.java
diff --git a/compiler/java/com/google/dart/compiler/ast/DartVariableStatement.java b/compiler/java/com/google/dart/compiler/ast/DartVariableStatement.java
index 7f5a5612548ecd6d310029d84b9192d08e432094..a0f322c28506484b41beb3066115e5228508d2c0 100644
--- a/compiler/java/com/google/dart/compiler/ast/DartVariableStatement.java
+++ b/compiler/java/com/google/dart/compiler/ast/DartVariableStatement.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.
 
@@ -39,9 +39,7 @@ public class DartVariableStatement extends DartStatement {
 
   @Override
   public void visitChildren(ASTVisitor<?> visitor) {
-    if (typeNode != null) {
-      typeNode.accept(visitor);
-    }
+    safelyVisitChild(typeNode, visitor);
     vars.accept(visitor);
   }