Reland of r19102: Check elimination improvement: propagation of state through phis is supported, Che

test/mjsunit/compiler/compare-map-elim.js

 // Copyright 2010 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
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@@ skipping 31 matching lines @@
 x(b);
 x(a);
 x(b);
 x(a);
 x(b);
 
 %OptimizeFunctionOnNextCall(x)
 
 x(a);
 x(b);