Remove an unused PassRefPtr ctor

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,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 46 matching lines @@
     if (LIKELY(ptr != 0))
         ptr->deref();
 }
 
 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); }
-    explicit PassRefPtr(T& ptr) : m_ptr(&ptr) { m_ptr->ref(); }
     // 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()) {}
     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));
@@ skipping 131 matching lines @@
 {
     return p.get();
 }
 
 } // namespace WTF
 
 using WTF::PassRefPtr;
 using WTF::adoptRef;
 
 #endif // WTF_PassRefPtr_h