Drop unused and undocumented dummy_ from SaveContext.

src/platform.h

 // Copyright 2012 the V8 project authors. 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.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 40 matching lines @@
 #include "v8globals.h"
 
 #ifdef __sun
 # ifndef signbit
 namespace std {
 int signbit(double x);
 }
 # endif
 #endif
 
-// GCC specific stuff
-#ifdef __GNUC__
-
-#define __GNUC_VERSION__ (__GNUC__ * 10000 + __GNUC_MINOR__ * 100)
-
-#endif  // __GNUC__
-
 // Microsoft Visual C++ specific stuff.
 #if V8_CC_MSVC
 
 #include "win32-headers.h"
 #include "win32-math.h"
 
 int strncasecmp(const char* s1, const char* s2, int n);
 
 inline int lrint(double flt) {
   int intgr;
@@ skipping 720 matching lines @@
   static uint16_t HToN(uint16_t value);
   static uint16_t NToH(uint16_t value);
   static uint32_t HToN(uint32_t value);
   static uint32_t NToH(uint32_t value);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_