Drop unused and undocumented dummy_ from SaveContext.

src/isolate.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 1388 matching lines @@
   Handle<Context> context() { return context_; }
   SaveContext* prev() { return prev_; }
 
   // Returns true if this save context is below a given JavaScript frame.
   bool IsBelowFrame(JavaScriptFrame* frame) {
     return (c_entry_fp_ == 0) || (c_entry_fp_ > frame->sp());
   }
 
  private:
   Handle<Context> context_;
-#if __GNUC_VERSION__ >= 40100 && __GNUC_VERSION__ < 40300
-  Handle<Context> dummy_;
-#endif
   SaveContext* prev_;
   Address c_entry_fp_;
 };
 
 
 class AssertNoContextChange BASE_EMBEDDED {
 #ifdef DEBUG
  public:
   AssertNoContextChange() :
       scope_(Isolate::Current()),
@@ skipping 83 matching lines @@
 
 // Mark the native context with out of memory.
 inline void Context::mark_out_of_memory() {
   native_context()->set_out_of_memory(HEAP->true_value());
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ISOLATE_H_