We use StoreOwnIC to initialize the object after creating a new object
with CreateObjectLiteral. CreateObjectLiteral stores kHoleNaNInt64
to indicate an uninitialized double field. When we actually try
to store a NaN value into that field later using StoreOwnIC, IC avoids
actually storing the new value since the existing value is "same as"
the value we try to write. The float comparison treats all NaNs as
equal. In this particular case, we should actually store the new value
since kHoleNaNInt64 value is used to represent an uninitialized field.

This cl just stores the new value even when the existing value is same
as the new value for double fields. The check is still required to
correctly track const fields.

Bug: chromium:1082293
Change-Id: Ib37061802f2403545cffa6d6fef08be074b0825d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2228886Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68167}