Use the field index to look up the descriptor for double fields, and add
a dependency on them.

Drive-by, fix store field optimisation to only emit the optimised direct
store for tagged fields, so that we don't accidentally insert
HeapNumbers into double fields (making them mutable).

Bug: v8:7700
Change-Id: I699c2a2e4e13194045139b9c995d05eb138c0e7c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3700071Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81077}