Made PassRefPtr move only and replaced new copies with moves.

third_party/WebKit/Source/wtf/PassRefPtr.h

 /*
  *  Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 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.
  *
  *  This library is distributed in the hope that it will be useful,
@@ skipping 53 matching lines @@
 }
 
 template <typename T>
 class PassRefPtr {
   DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
 
  public:
   PassRefPtr() : m_ptr(nullptr) {}
   PassRefPtr(std::nullptr_t) : m_ptr(nullptr) {}
   PassRefPtr(T* ptr) : m_ptr(ptr) { refIfNotNull(ptr); }
-  // It somewhat breaks the type system to allow transfer of ownership out of
-  // a const PassRefPtr. However, it makes it much easier to work with
-  // PassRefPtr temporaries, and we don't have a need to use real const
-  // PassRefPtrs anyway.
-  PassRefPtr(const PassRefPtr& o) : m_ptr(o.leakRef()) {}
   PassRefPtr(PassRefPtr&& o) : m_ptr(o.leakRef()) {}
   template <typename U>
   PassRefPtr(const PassRefPtr<U>& o, EnsurePtrConvertibleArgDecl(U, T))
       : m_ptr(o.leakRef()) {}
 
   ALWAYS_INLINE ~PassRefPtr() { derefIfNotNull(m_ptr); }
 
   template <typename U>
   PassRefPtr(const RefPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));
   template <typename U>
@@ skipping 130 matching lines @@
 inline T* getPtr(const PassRefPtr<T>& p) {
   return p.get();
 }
 
 }  // namespace WTF
 
 using WTF::PassRefPtr;
 using WTF::adoptRef;
 
 #endif  // WTF_PassRefPtr_h