Remove preemption thread and API

src/execution.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 796 matching lines @@
   }
 
   return Handle<String>::cast(result);
 }
 
 
 static Object* RuntimePreempt(Isolate* isolate) {
   // Clear the preempt request flag.
   isolate->stack_guard()->Continue(PREEMPT);
 
-  ContextSwitcher::PreemptionReceived();
-
 #ifdef ENABLE_DEBUGGER_SUPPORT
   if (isolate->debug()->InDebugger()) {
     // If currently in the debugger don't do any actual preemption but record
     // that preemption occoured while in the debugger.
     isolate->debug()->PreemptionWhileInDebugger();
   } else {
     // Perform preemption.
     v8::Unlocker unlocker(reinterpret_cast<v8::Isolate*>(isolate));
     Thread::YieldCPU();
   }
@@ skipping 125 matching lines @@
     ASSERT(FLAG_concurrent_recompilation);
     stack_guard->Continue(INSTALL_CODE);
     isolate->optimizing_compiler_thread()->InstallOptimizedFunctions();
   }
   isolate->runtime_profiler()->OptimizeNow();
   return isolate->heap()->undefined_value();
 }
 
 
 } }  // namespace v8::internal