Made RefPtr constructor only accept PassRefPtr rvalues.

third_party/WebKit/Source/platform/PODRedBlackTree.h

 /*
  * Copyright (C) 2010 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 120 matching lines @@
 #ifndef NDEBUG
         ,
         verbose_debugging_(false)
 #endif
   {
   }
 
   // Constructs a new red-black tree, allocating temporary objects
   // from the given PODArena.
   explicit PODRedBlackTree(PassRefPtr<PODFreeListArena<Node>> arena)
-      : arena_(arena),
+      : arena_(std::move(arena)),
         root_(0),
         needs_full_ordering_comparisons_(false)
 #ifndef NDEBUG
         ,
         verbose_debugging_(false)
 #endif
   {
   }
 
   virtual ~PODRedBlackTree() {}
@@ skipping 634 matching lines @@
   Node* root_;
   bool needs_full_ordering_comparisons_;
 #ifndef NDEBUG
   bool verbose_debugging_;
 #endif
 };
 
 }  // namespace blink
 
 #endif  // PODRedBlackTree_h