[Isolates] Add a pointer to Heap to a meta map.

src/heap.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 1103 matching lines @@
   int get_min_in_mutator() { return min_in_mutator_; }
 
   MarkCompactCollector* mark_compact_collector() {
     return &mark_compact_collector_;
   }
 
   ExternalStringTable* external_string_table() {
     return &external_string_table_;
   }
 
+  inline Isolate* isolate();
+
  private:
   Heap();
 
   // TODO(isolates): Technically this can be calculated directly from
   //                 any pointer to Heap.
   Isolate* isolate_;
 
   int reserved_semispace_size_;
   int max_semispace_size_;
   int initial_semispace_size_;
@@ skipping 901 matching lines @@
   SubCache* caches_[kNumberOfCaches];
   DISALLOW_COPY_AND_ASSIGN(TranscendentalCache);
 };
 
 
 } }  // namespace v8::internal
 
 #undef HEAP
 
 #endif  // V8_HEAP_H_