Fix determining of JS lower stack bottom used in profiler's JS stack tracer to work with Chromium.

src/top.cc

 // 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 73 matching lines @@
 
 void Top::Iterate(ObjectVisitor* v) {
   ThreadLocalTop* current_t = &thread_local_;
   Iterate(v, current_t);
 }
 
 
 void Top::InitializeThreadLocal() {
   thread_local_.c_entry_fp_ = 0;
   thread_local_.handler_ = 0;
+#ifdef ENABLE_LOGGING_AND_PROFILING
+  thread_local_.js_entry_sp_ = 0;
+#endif
   thread_local_.stack_is_cooked_ = false;
   thread_local_.try_catch_handler_ = NULL;
   thread_local_.context_ = NULL;
   thread_local_.external_caught_exception_ = false;
   thread_local_.failed_access_check_callback_ = NULL;
   clear_pending_exception();
   clear_pending_message();
   clear_scheduled_exception();
   thread_local_.save_context_ = NULL;
   thread_local_.catcher_ = NULL;
@@ skipping 820 matching lines @@
   Top::break_access_->Lock();
 }
 
 
 ExecutionAccess::~ExecutionAccess() {
   Top::break_access_->Unlock();
 }
 
 
 } }  // namespace v8::internal