Refactor the compiling pipeline.

test/mjsunit/compiler/concurrent-proto-change.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 36 matching lines @@
 assertEquals(1, f(o));
 // Change the prototype chain after compile graph has been created.
 o.__proto__.__proto__ = { bar: function() { return 2; } };
 // At this point, concurrent recompilation thread has not yet done its job.
 assertUnoptimized(f, "no sync");
 // Let the background thread proceed.
 %UnblockConcurrentRecompilation();
 // Optimization eventually bails out due to map dependency.
 assertUnoptimized(f, "sync");
 assertEquals(2, f(o));
+//Clear type info for stress runs.
+%ClearFunctionTypeFeedback(f);