Make assertion scopes thread safe.

src/checks.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 18 matching lines @@
 
 #include "v8.h"
 
 #include "platform.h"
 
 // TODO(isolates): is it necessary to lift this?
 static int fatal_error_handler_nesting_depth = 0;
 
 // Contains protection against recursive calls (faults while handling faults).
 extern "C" void V8_Fatal(const char* file, int line, const char* format, ...) {
+  i::AllowHandleDereference allow_deref;
+  i::AllowDeferredHandleDereference allow_deferred_deref;
   fflush(stdout);
   fflush(stderr);
   fatal_error_handler_nesting_depth++;
   // First time we try to print an error message
   if (fatal_error_handler_nesting_depth < 2) {
     i::OS::PrintError("\n\n#\n# Fatal error in %s, line %d\n# ", file, line);
     va_list arguments;
     va_start(arguments, format);
     i::OS::VPrintError(format, arguments);
     va_end(arguments);
@@ skipping 53 matching lines @@
 
 
 namespace v8 { namespace internal {
 
   bool EnableSlowAsserts() { return FLAG_enable_slow_asserts; }
 
   intptr_t HeapObjectTagMask() { return kHeapObjectTagMask; }
 
 } }  // namespace v8::internal