[turbofan] Add JSStackCheck into loop bodies.

test/cctest/test-debug.cc

 // Copyright 2012 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 6679 matching lines @@
 
   v8::Debug::SetMessageHandler(
       SendCommandThread::CountingAndSignallingMessageHandler);
   send_command_thread_ = new SendCommandThread(isolate);
   send_command_thread_->Start();
 
   v8::Handle<v8::FunctionTemplate> start =
       v8::FunctionTemplate::New(isolate, StartSendingCommands);
   env->Global()->Set(v8_str("start"), start->GetFunction());
 
-  i::FLAG_turbo_osr = false;  // TODO(titzer): interrupts in TF loops.
   CompileRun("start(); while (true) { }");
 
   CHECK_EQ(20, counting_message_handler_counter);
 
   v8::Debug::SetMessageHandler(NULL);
   CheckDebuggerUnloaded();
 }
 
 
 struct BacktraceData {
@@ skipping 879 matching lines @@
       "let y = 2;               \n"
       "debugger;                \n"
       "x * y",
       30);
   ExpectInt32(
       "x = 1; y = 2; \n"
       "debugger;"
       "x * y",
       30);
 }