Make Failure inherit from MaybeObject instead of Object.

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 541 matching lines @@
 void Logger::LogRuntime(Vector<const char> format, JSArray* args) {
 #ifdef ENABLE_LOGGING_AND_PROFILING
   if (!Log::IsEnabled() || !FLAG_log_runtime) return;
   HandleScope scope;
   LogMessageBuilder msg;
   for (int i = 0; i < format.length(); i++) {
     char c = format[i];
     if (c == '%' && i <= format.length() - 2) {
       i++;
       ASSERT('0' <= format[i] && format[i] <= '9');
-      Object* obj = args->GetElement(format[i] - '0');
+      MaybeObject* maybe = args->GetElement(format[i] - '0');
+      Object* obj;
+      if (!maybe->ToObject(&obj)) {
+        msg.Append("<exception>");
+        continue;
+      }
       i++;
       switch (format[i]) {
         case 's':
           msg.AppendDetailed(String::cast(obj), false);
           break;
         case 'S':
           msg.AppendDetailed(String::cast(obj), true);
           break;
         case 'r':
           Logger::LogRegExpSource(Handle<JSRegExp>(JSRegExp::cast(obj)));
@@ skipping 1068 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