Allow assertions to be enabled in Blink Release builds.

Source/core/dom/ContainerNode.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010, 2011, 2013 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 200 matching lines @@
     void attachChildren(const AttachContext& = AttachContext());
     void detachChildren(const AttachContext& = AttachContext());
 
     bool getUpperLeftCorner(FloatPoint&) const;
     bool getLowerRightCorner(FloatPoint&) const;
 
     RawPtrWillBeMember<Node> m_firstChild;
     RawPtrWillBeMember<Node> m_lastChild;
 };
 
-#ifndef NDEBUG
+#if ENABLE(ASSERT)
 bool childAttachedAllowedWhenAttachingChildren(ContainerNode*);
 #endif
 
 DEFINE_NODE_TYPE_CASTS(ContainerNode, isContainerNode());
 
 inline bool ContainerNode::hasChildCount(unsigned count) const
 {
     Node* child = m_firstChild;
     while (count && child) {
         child = child->nextSibling();
@@ skipping 87 matching lines @@
 inline void getChildNodes(Node& node, NodeVector& nodes)
 {
     ASSERT(!nodes.size());
     for (Node* child = node.firstChild(); child; child = child->nextSibling())
         nodes.append(child);
 }
 
 } // namespace WebCore
 
 #endif // ContainerNode_h