Patch for allowing several V8 instances in process:...

src/factory.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 297 matching lines @@
   // Installs interceptors on the instance.  'desc' is a function template,
   // and instance is an object instance created by the function of this
   // function template.
   static void ConfigureInstance(Handle<FunctionTemplateInfo> desc,
                                 Handle<JSObject> instance,
                                 bool* pending_exception);
 
 #define ROOT_ACCESSOR(type, name, camel_name)                                  \
   static inline Handle<type> name() {                                          \
     return Handle<type>(bit_cast<type**, Object**>(                            \
-        &Heap::roots_[Heap::k##camel_name##RootIndex]));                       \
+        &v8_context()->heap_data_.roots_[Heap::k##camel_name##RootIndex]));    \
   }
   ROOT_LIST(ROOT_ACCESSOR)
 #undef ROOT_ACCESSOR_ACCESSOR
 
 #define SYMBOL_ACCESSOR(name, str) \
   static inline Handle<String> name() {                                        \
     return Handle<String>(bit_cast<String**, Object**>(                        \
-        &Heap::roots_[Heap::k##name##RootIndex]));                             \
+        &v8_context()->heap_data_.roots_[Heap::k##name##RootIndex]));          \
   }
   SYMBOL_LIST(SYMBOL_ACCESSOR)
 #undef SYMBOL_ACCESSOR
 
   static Handle<String> hidden_symbol() {
-    return Handle<String>(&Heap::hidden_symbol_);
+    return Handle<String>(&v8_context()->heap_data_.hidden_symbol_);
   }
 
   static Handle<SharedFunctionInfo> NewSharedFunctionInfo(Handle<String> name);
 
   static Handle<NumberDictionary> DictionaryAtNumberPut(
       Handle<NumberDictionary>,
       uint32_t key,
       Handle<Object> value);
 
 #ifdef ENABLE_DEBUGGER_SUPPORT
@@ skipping 39 matching lines @@
   // Update the map cache in the global context with (keys, map)
   static Handle<MapCache> AddToMapCache(Handle<Context> context,
                                         Handle<FixedArray> keys,
                                         Handle<Map> map);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FACTORY_H_