This makes sure that the deoptimizer preserves the exact bit pattern of
floating-point values (both 32-bit and 64-bit) up to the point where a
potential {HeapNumber} is allocated. It in turn allows us to correctly
recognize the {hole_nan_value} when stored into a {FixedDouleArray}.

R=jarin@chromium.org
TEST=mjsunit/regress/regress-crbug-684208
BUG=chromium:684208

Review-Url: https://codereview.chromium.org/2652303002
Cr-Commit-Position: refs/heads/master@{#42679}