Prototype these two instructions on ia32. They are movss and movsd
respectively, so the implementation is pretty simple, as we support
these instructions already.

Bug: v8:11038
Change-Id: Iebf4afab2bf1edfb4b14a4855d5036677f999ca9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2486232Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70634}