Fix reporting of impossible nested calls of DOM functions.

src/log.cc

 // Copyright 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 146 matching lines @@
 
   const Address functionAddr =
       sample->fp + JavaScriptFrameConstants::kFunctionOffset;
   if (SafeStackFrameIterator::IsWithinBounds(sample->sp, js_entry_sp,
                                              functionAddr)) {
     sample->function = Memory::Address_at(functionAddr) - kHeapObjectTag;
   }
 
   int i = 0;
   const Address callback = VMState::external_callback();
-  if (callback != NULL) {
+  // Surprisingly, PC can point _exactly_ to callback start, with good
+  // probability, and this will result in reporting fake nested
+  // callback call.
+  if (callback != NULL && callback != sample->pc) {
     sample->stack[i++] = callback;
   }
 
   SafeStackTraceFrameIterator it(sample->fp, sample->sp,
                                  sample->sp, js_entry_sp);
   while (!it.done() && i < TickSample::kMaxFramesCount) {
     sample->stack[i++] =
         reinterpret_cast<Address>(it.frame()->function_slot_object()) -
             kHeapObjectTag;
     it.Advance();
@@ skipping 1468 matching lines @@
   }
   // Otherwise, if the sliding state window computation has not been
   // started we do it now.
   if (sliding_state_window_ == NULL) {
     sliding_state_window_ = new SlidingStateWindow();
   }
 #endif
 }
 
 } }  // namespace v8::internal