Used to be named FastFixedArrayForEachBody. Rename to remove the 'fixed'
part since it can also be a PropertyArray (i.e not a FixedArray).

Rename BuildFastFixedArrayForEach to also remove the 'fixed'.

Bug: v8:10506, v8:6949
Change-Id: I840edf802d334b9ca930f3022553c476e2dca34a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2202910Reviewed-by: Dan Elphick <delphick@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67886}