Allocate optimizing compiler thread only when necessary.

src/isolate.h

 // Copyright 2012 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 1081 matching lines @@
 
   void IterateDeferredHandles(ObjectVisitor* visitor);
   void LinkDeferredHandles(DeferredHandles* deferred_handles);
   void UnlinkDeferredHandles(DeferredHandles* deferred_handles);
 
 #ifdef DEBUG
   bool IsDeferredHandle(Object** location);
 #endif  // DEBUG
 
   OptimizingCompilerThread* optimizing_compiler_thread() {
-    return &optimizing_compiler_thread_;
+    return optimizing_compiler_thread_;
   }
 
   // PreInits and returns a default isolate. Needed when a new thread tries
   // to create a Locker for the first time (the lock itself is in the isolate).
   // TODO(svenpanne) This method is on death row...
   static v8::Isolate* GetDefaultIsolateForLocking();
 
   MarkingThread** marking_threads() {
     return marking_thread_;
   }
@@ skipping 249 matching lines @@
   // preprocessor defines. Make sure the offsets of these fields agree
   // between compilation units.
 #define ISOLATE_FIELD_OFFSET(type, name, ignored)                              \
   static const intptr_t name##_debug_offset_;
   ISOLATE_INIT_LIST(ISOLATE_FIELD_OFFSET)
   ISOLATE_INIT_ARRAY_LIST(ISOLATE_FIELD_OFFSET)
 #undef ISOLATE_FIELD_OFFSET
 #endif
 
   DeferredHandles* deferred_handles_head_;
-  OptimizingCompilerThread optimizing_compiler_thread_;
+  OptimizingCompilerThread* optimizing_compiler_thread_;
   MarkingThread** marking_thread_;
   SweeperThread** sweeper_thread_;
 
   // Counts deopt points if deopt_every_n_times is enabled.
   unsigned int stress_deopt_count_;
 
   friend class ExecutionAccess;
   friend class HandleScopeImplementer;
   friend class IsolateInitializer;
   friend class MarkingThread;
@@ skipping 149 matching lines @@
 
 // Mark the native context with out of memory.
 inline void Context::mark_out_of_memory() {
   native_context()->set_out_of_memory(GetIsolate()->heap()->true_value());
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ISOLATE_H_