Flush the runtime %DebugPrint output. Should have no performance impact,...

src/runtime.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 3189 matching lines @@
            frame->fp(), frame->sp(), frame->pp());
   } else {
     PrintF("DebugPrint: ");
   }
   args[0]->Print();
 #else
   // ShortPrint is available in release mode. Print is not.
   args[0]->ShortPrint();
 #endif
   PrintF("\n");
+  Flush();
 
   return args[0];  // return TOS
 }
 
 
 static Object* Runtime_DebugTrace(Arguments args) {
   ASSERT(args.length() == 1);
   NoHandleAllocation ha;
   Top::PrintStack();
   return args[0];  // return TOS
@@ skipping 1740 matching lines @@
 
 void Runtime::PerformGC(Object* result) {
   Failure* failure = Failure::cast(result);
   // Try to do a garbage collection; ignore it if it fails. The C
   // entry stub will throw an out-of-memory exception in that case.
   Heap::CollectGarbage(failure->requested(), failure->allocation_space());
 }
 
 
 } }  // namespace v8::internal