There is some code common to both wide and extra wide that we are
able to hoist up since they do not affect the flags after testing
to see which version to use.

Bug: v8:9771
Change-Id: Idb5ce4bd0dfcb5b38d9bc6e4257f763de3bf3567
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1826725Reviewed-by: Dan Elphick <delphick@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64008}