Properly reset external catcher if exception couldn't be externally caught.

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 717 matching lines @@
 Failure* Top::Throw(Object* exception, MessageLocation* location) {
   DoThrow(exception, location, NULL);
   return Failure::Exception();
 }
 
 
 Failure* Top::ReThrow(MaybeObject* exception, MessageLocation* location) {
   bool can_be_caught_externally = false;
   ShouldReportException(&can_be_caught_externally,
                         is_catchable_by_javascript(exception));
-  if (can_be_caught_externally) {
-    thread_local_.catcher_ = try_catch_handler();
-  }
+  thread_local_.catcher_ = can_be_caught_externally ?
+      try_catch_handler() : NULL;
 
   // Set the exception being re-thrown.
   set_pending_exception(exception);
   return Failure::Exception();
 }
 
 
 Failure* Top::ThrowIllegalOperation() {
   return Throw(Heap::illegal_access_symbol());
 }
@@ skipping 155 matching lines @@
   thread_local_.pending_message_ = message;
   if (!message_obj.is_null()) {
     thread_local_.pending_message_obj_ = *message_obj;
     if (location != NULL) {
       thread_local_.pending_message_script_ = *location->script();
       thread_local_.pending_message_start_pos_ = location->start_pos();
       thread_local_.pending_message_end_pos_ = location->end_pos();
     }
   }
 
-  if (can_be_caught_externally) {
-    thread_local_.catcher_ = try_catch_handler();
-  }
+  // Do not forget to clean catcher_ if currently thrown exception cannot
+  // be caught.  If necessary, ReThrow will update the catcher.
+  thread_local_.catcher_ = can_be_caught_externally ?
+      try_catch_handler() : NULL;
 
   // NOTE: Notifying the debugger or generating the message
   // may have caused new exceptions. For now, we just ignore
   // that and set the pending exception to the original one.
   if (is_object) {
     set_pending_exception(*exception_handle);
   } else {
     // Failures are not on the heap so they neither need nor work with handles.
     ASSERT(exception_handle->IsFailure());
     set_pending_exception(exception);
@@ skipping 214 matching lines @@
 #ifdef V8_TARGET_ARCH_ARM
   thread_local_.simulator_ = Simulator::current();
 #elif V8_TARGET_ARCH_MIPS
   thread_local_.simulator_ = assembler::mips::Simulator::current();
 #endif
 #endif
   return from + sizeof(thread_local_);
 }
 
 } }  // namespace v8::internal