Refactor the compiling pipeline.

test/mjsunit/concurrent-initial-prototype-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 37 matching lines @@
 // Invalidate current initial object map after compile graph has been created.
 Object.prototype[1] = 1.5;
 assertEquals(2, f1(arr, 1));
 // Not yet optimized since concurrent recompilation is blocked.
 assertUnoptimized(f1, "no sync");
 // Let concurrent recompilation proceed.
 %UnblockConcurrentRecompilation();
 // Sync with background thread to conclude optimization, which bails out
 // due to map dependency.
 assertUnoptimized(f1, "sync");
+//Clear type info for stress runs.
+%ClearFunctionTypeFeedback(f1);