Issue 3931. Visit children nodes safely.

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

Index: compiler/java/com/google/dart/compiler/ast/DartSwitchMember.java
diff --git a/compiler/java/com/google/dart/compiler/ast/DartSwitchMember.java b/compiler/java/com/google/dart/compiler/ast/DartSwitchMember.java
index 690b6140234fefbf7c47263a37153af19f61fc0d..74a777ee8539a9d0d080764f96a58802a26948de 100644
--- a/compiler/java/com/google/dart/compiler/ast/DartSwitchMember.java
+++ b/compiler/java/com/google/dart/compiler/ast/DartSwitchMember.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.
 
@@ -29,9 +29,7 @@ public abstract class DartSwitchMember extends DartNode {
 
   @Override
   public void visitChildren(ASTVisitor<?> visitor) {
-    if (label != null) {
-      label.accept(visitor);
-    }
+    safelyVisitChild(label, visitor);
     statements.accept(visitor);
   }
 }