For stack-switching, we create a callable object from the
WasmResume builtin and pass that as the onFulfilled argument
of Promise#then. We don't need to create this callable object each time
we suspend. Instead, create it when we initialize the Suspender object
and store it there.

R=jkummerow@chromium.org
CC=fgm@chromium.org

Bug: v8:12191
Change-Id: If8495493a71794cddc81b21a17a821fed8f4ede7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3579162Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79930}