Rewrite Shadow DOM distribution engine to support partial synchronous distribution for v1

third_party/WebKit/Source/core/dom/shadow/FlatTreeTraversal.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 107 matching lines @@
     static Node& lastWithinOrSelf(const Node&);
 
 private:
     enum TraversalDirection {
         TraversalDirectionForward,
         TraversalDirectionBackward
     };
 
     static void assertPrecondition(const Node& node)
     {
-#if DCHECK_IS_ON()
         DCHECK(!node.needsDistributionRecalc());
         DCHECK(node.canParticipateInFlatTree());
-#endif
     }
 
     static void assertPostcondition(const Node* node)
     {
 #if DCHECK_IS_ON()
         if (node)
             assertPrecondition(*node);
 #endif
     }
 
@@ skipping 163 matching lines @@
 }
 
 inline Node* FlatTreeTraversal::traverseLastChild(const Node& node)
 {
     return traverseChild(node, TraversalDirectionBackward);
 }
 
 } // namespace blink
 
 #endif