Store API callback entry address prior to entering a callback.

src/log-inl.h

 // Copyright 2006-2009 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 37 matching lines @@
     case COMPILER:
       return "COMPILER";
     case OTHER:
       return "OTHER";
     default:
       UNREACHABLE();
       return NULL;
   }
 }
 
-VMState::VMState(StateTag state) : disabled_(true) {
+VMState::VMState(StateTag state) : disabled_(true), external_callback_(NULL) {
   if (!Logger::is_logging()) {
     return;
   }
 
   disabled_ = false;
 #if !defined(ENABLE_HEAP_PROTECTION)
   // When not protecting the heap, there is no difference between
   // EXTERNAL and OTHER.  As an optimization in that case, we will not
   // perform EXTERNAL->OTHER transitions through the API.  We thus
   // compress the two states into one.
@@ skipping 48 matching lines @@
     }
   }
 #endif
 }
 #endif
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_LOG_INL_H_