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

src/contexts.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 76 matching lines @@
   V(MAKE_MESSAGE_FUN_INDEX, JSFunction, make_message_fun) \
   V(GET_STACK_TRACE_LINE_INDEX, JSFunction, get_stack_trace_line_fun) \
   V(CONFIGURE_GLOBAL_INDEX, JSFunction, configure_global_fun) \
   V(FUNCTION_CACHE_INDEX, JSObject, function_cache) \
   V(RUNTIME_CONTEXT_INDEX, Context, runtime_context) \
   V(CALL_AS_FUNCTION_DELEGATE_INDEX, JSFunction, call_as_function_delegate) \
   V(EMPTY_SCRIPT_INDEX, Script, empty_script) \
   V(SCRIPT_FUNCTION_INDEX, JSFunction, script_function) \
   V(CONTEXT_EXTENSION_FUNCTION_INDEX, JSFunction, context_extension_function) \
   V(OUT_OF_MEMORY_INDEX, Object, out_of_memory) \
-  V(MAP_CACHE_INDEX, Object, map_cache)
+  V(MAP_CACHE_INDEX, Object, map_cache) \
+  V(CONTEXT_DATA_INDEX, Object, data)
 
 // JSFunctions are pairs (context, function code), sometimes also called
 // closures. A Context object is used to represent function contexts and
 // dynamically pushed 'with' contexts (or 'scopes' in ECMA-262 speak).
 //
 // At runtime, the contexts build a stack in parallel to the execution
 // stack, with the top-most context being the current context. All contexts
 // have the following slots:
 //
 // [ closure   ]  This is the current function. It is the same for all
@@ skipping 98 matching lines @@
     GET_STACK_TRACE_LINE_INDEX,
     CONFIGURE_GLOBAL_INDEX,
     FUNCTION_CACHE_INDEX,
     RUNTIME_CONTEXT_INDEX,
     CALL_AS_FUNCTION_DELEGATE_INDEX,
     EMPTY_SCRIPT_INDEX,
     SCRIPT_FUNCTION_INDEX,
     CONTEXT_EXTENSION_FUNCTION_INDEX,
     OUT_OF_MEMORY_INDEX,
     MAP_CACHE_INDEX,
+    CONTEXT_DATA_INDEX,
     GLOBAL_CONTEXT_SLOTS
   };
 
   // Direct slot access.
   JSFunction* closure() { return JSFunction::cast(get(CLOSURE_INDEX)); }
   void set_closure(JSFunction* closure) { set(CLOSURE_INDEX, closure); }
 
   Context* fcontext() { return Context::cast(get(FCONTEXT_INDEX)); }
   void set_fcontext(Context* context) { set(FCONTEXT_INDEX, context); }
 
@@ skipping 102 matching lines @@
 #ifdef DEBUG
   // Bootstrapping-aware type checks.
   static bool IsBootstrappingOrContext(Object* object);
   static bool IsBootstrappingOrGlobalObject(Object* object);
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_CONTEXTS_H_