Import Reversed adapter from Chromium and use it in v8.

src/base/macros.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_BASE_MACROS_H_
 #define V8_BASE_MACROS_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 210 matching lines @@
 template <class Dest, class Source>
 V8_INLINE Dest bit_cast(Source const& source) {
   COMPILE_ASSERT(sizeof(Dest) == sizeof(Source), VerifySizesAreEqual);
 
   Dest dest;
   memcpy(&dest, &source, sizeof(dest));
   return dest;
 }
 
 
+// Put this in the private: declarations for a class to be unassignable.
+#define DISALLOW_ASSIGN(TypeName) void operator=(const TypeName&)
+
+
 // A macro to disallow the evil copy constructor and operator= functions
 // This should be used in the private: declarations for a class
 #define DISALLOW_COPY_AND_ASSIGN(TypeName)  \
   TypeName(const TypeName&) V8_DELETE;      \
   void operator=(const TypeName&) V8_DELETE
 
 
 // A macro to disallow all the implicit constructors, namely the
 // default constructor, copy constructor and operator= functions.
 //
@@ skipping 172 matching lines @@
 }
 
 template <>
 inline bool is_fundamental<uint8_t>() {
   return true;
 }
 }
 }  // namespace v8::base
 
 #endif   // V8_BASE_MACROS_H_