Run Crankshaft on a separate thread.

test/mjsunit/regress/regress-1118.js

 // Copyright 2011 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 32 matching lines @@
 
 // Optimization status (see runtime.cc):
 // 1 - yes, 2 - no, 3 - always, 4 - never.
 
 // This function should be optimized via OSR.
 function h() {
   var optstatus = %GetOptimizationStatus(h);
   if (optstatus == 4) {
     // Optimizations are globally disabled; just run once.
     g();
+  } else if (optstatus == 5) {
+    // Optimizations are being carried out concurrently, this test
+    // will probably timeout.
+    g();
   } else {
     // Run for a bit as long as h is unoptimized.
     while (%GetOptimizationStatus(h) == 2) {
       for (var j = 0; j < 100; j++) g();
     }
     g();
   }
 }
 
 h();
 o = new B();
 assertThrows("h()");