Add a test for debug break while running in an infinite loop...

src/debug.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 1821 matching lines @@
       restarter_frame_function_pointer;
 }
 
 
 bool Debug::IsDebugGlobal(GlobalObject* global) {
   return IsLoaded() && global == Debug::debug_context()->global();
 }
 
 
 void Debug::ClearMirrorCache() {
+  PostponeInterruptsScope postpone;
   HandleScope scope;
   ASSERT(Top::context() == *Debug::debug_context());
 
   // Clear the mirror cache.
   Handle<String> function_name =
       Factory::LookupSymbol(CStrVector("ClearMirrorCache"));
   Handle<Object> fun(Top::global()->GetPropertyNoExceptionThrown(
       *function_name));
   ASSERT(fun->IsJSFunction());
   bool caught_exception;
@@ skipping 1208 matching lines @@
     {
       Locker locker;
       Debugger::CallMessageDispatchHandler();
     }
   }
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal