Add the ability to set embedder data on created contexts from the API

src/bootstrapper.cc

 // 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 815 matching lines @@
   Handle<JSFunction> delegate =
       Factory::NewFunction(Factory::empty_symbol(), JS_OBJECT_TYPE,
                            JSObject::kHeaderSize, code, true);
   global_context()->set_call_as_function_delegate(*delegate);
   delegate->shared()->DontAdaptArguments();
 
   global_context()->set_special_function_table(Heap::empty_fixed_array());
 
   // Initialize the out of memory slot.
   global_context()->set_out_of_memory(Heap::false_value());
+
+  // Initialize the data slot.
+  global_context()->set_data(Heap::undefined_value());
 }
 
 
 bool Genesis::CompileBuiltin(int index) {
   Vector<const char> name = Natives::GetScriptName(index);
   Handle<String> source_code = Bootstrapper::NativesSourceLookup(index);
   return CompileNative(name, source_code);
 }
 
 
@@ skipping 701 matching lines @@
 }
 
 
 // Restore statics that are thread local.
 char* Genesis::RestoreState(char* from) {
   current_ = *reinterpret_cast<Genesis**>(from);
   return from + sizeof(current_);
 }
 
 } }  // namespace v8::internal