This makes sure that the return type of the aforementioned heap views is
always {float?} and {double?} respectively, independent of the type of
the value passed to the store. It fixes validation failures due to bogus
(and redundant) conversion expressions being emitted.

R=clemensb@chromium.org
TEST=mjsunit/asm/regress-1027595
BUG=chromium:1027595

Change-Id: I037613afc643ac1b04ae4a943e42dc1823ad5bdf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1932374Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65151}