Simplify inDetach() assert and make it stronger.

Source/core/dom/Node.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) 2004-2011, 2014 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * 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
@@ skipping 526 matching lines @@
 
     // Attaches this node to the layout tree. This calculates the style to be applied to the node and creates an
     // appropriate LayoutObject which will be inserted into the tree (except when the style has display: none). This
     // makes the node visible in the FrameView.
     virtual void attach(const AttachContext& = AttachContext());
 
     // Detaches the node from the layout tree, making it invisible in the rendered view. This method will remove
     // the node's layout object from the layout tree and delete it.
     virtual void detach(const AttachContext& = AttachContext());
 
-#if ENABLE(ASSERT)
-    bool inDetach() const;
-#endif
-
     void reattach(const AttachContext& = AttachContext());
     void lazyReattachIfAttached();
 
     // Returns true if recalcStyle should be called on the object, if there is such a method (on Document and Element).
     bool shouldCallRecalcStyle(StyleRecalcChange);
 
     // Wrapper for nodes that don't have a layoutObject, but still cache the style (like HTMLOptionElement).
     ComputedStyle* mutableComputedStyle() const;
     const ComputedStyle* computedStyle() const;
     const ComputedStyle* parentComputedStyle() const;
@@ skipping 354 matching lines @@
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showNode(const blink::Node*);
 void showTree(const blink::Node*);
 void showNodePath(const blink::Node*);
 #endif
 
 #endif // Node_h