Check aliased FP registers when constructing the {to_be_live} set from
multiple predecessors.

R=sigurds@chromium.org

Bug: chromium:1029642
Change-Id: I3db7b705ad5689bd8321aebc5e9c5f364951870b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1958054Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65412}