Issue 3931. Visit children nodes safely.

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

Index: compiler/java/com/google/dart/compiler/ast/DartConditional.java
diff --git a/compiler/java/com/google/dart/compiler/ast/DartConditional.java b/compiler/java/com/google/dart/compiler/ast/DartConditional.java
index 04a7a8eaff495af4b648d7993e3e25df967bad69..9e8a3d108155d7e13123ecc974e5fcce2dab37aa 100644
--- a/compiler/java/com/google/dart/compiler/ast/DartConditional.java
+++ b/compiler/java/com/google/dart/compiler/ast/DartConditional.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.
 
@@ -34,9 +34,9 @@ public class DartConditional extends DartExpression {
 
   @Override
   public void visitChildren(ASTVisitor<?> visitor) {
-    condition.accept(visitor);
-    thenExpr.accept(visitor);
-    elseExpr.accept(visitor);
+    safelyVisitChild(condition, visitor);
+    safelyVisitChild(thenExpr, visitor);
+    safelyVisitChild(elseExpr, visitor);
   }
 
   @Override