Introduce concurrent on-stack replacement.

test/mjsunit/regress/regress-map-invalidation-2.js

 // Copyright 2013 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 21 matching lines @@
 function g() {
   var outer = { foo: 1 };
   function f() {
     var n = outer.foo;
     for (var i = 0; i < 100000; i++) {
       n += c.x + outer.foo;
     }
     var o2 = [{ x: 1.5, y: 1 }];
     return o2;
   }
+  // Clear type feedback from previous stress runs.
+  %ClearFunctionTypeFeedback(f);
   return f;
 }
 
 var fun = g();
 fun();
 assertOptimized(fun);
 fun();