Push version 2.5.7 to trunk....

src/execution.h

 // Copyright 2006-2008 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 171 matching lines @@
   static void DebugCommand();
 #endif
   static void Continue(InterruptFlag after_what);
 
   // This provides an asynchronous read of the stack limits for the current
   // thread.  There are no locks protecting this, but it is assumed that you
   // have the global V8 lock if you are using multiple V8 threads.
   static uintptr_t climit() {
     return thread_local_.climit_;
   }
+  static uintptr_t real_climit() {
+    return thread_local_.real_climit_;
+  }
   static uintptr_t jslimit() {
     return thread_local_.jslimit_;
   }
   static uintptr_t real_jslimit() {
     return thread_local_.real_jslimit_;
   }
   static Address address_of_jslimit() {
     return reinterpret_cast<Address>(&thread_local_.jslimit_);
   }
   static Address address_of_real_jslimit() {
@@ skipping 104 matching lines @@
     StackGuard::DisableInterrupts();
   }
 
   ~PostponeInterruptsScope() {
     if (--StackGuard::thread_local_.postpone_interrupts_nesting_ == 0) {
       StackGuard::EnableInterrupts();
     }
   }
 };
 
-
-class GCExtension : public v8::Extension {
- public:
-  GCExtension() : v8::Extension("v8/gc", kSource) {}
-  virtual v8::Handle<v8::FunctionTemplate> GetNativeFunction(
-      v8::Handle<v8::String> name);
-  static v8::Handle<v8::Value> GC(const v8::Arguments& args);
- private:
-  static const char* const kSource;
-};
-
-
-class ExternalizeStringExtension : public v8::Extension {
- public:
-  ExternalizeStringExtension() : v8::Extension("v8/externalize", kSource) {}
-  virtual v8::Handle<v8::FunctionTemplate> GetNativeFunction(
-      v8::Handle<v8::String> name);
-  static v8::Handle<v8::Value> Externalize(const v8::Arguments& args);
-  static v8::Handle<v8::Value> IsAscii(const v8::Arguments& args);
- private:
-  static const char* const kSource;
-};
-
 } }  // namespace v8::internal
 
 #endif  // V8_EXECUTION_H_