Avoid writing NumberOfElements to HashTable when it hasn't changed as
the HashTable could be in RO_SPACE and this operation will crash.

Bug: v8:841592
Change-Id: Iffadd567fc10aa9cd13d953da81275464b16c6c0
Reviewed-on: https://chromium-review.googlesource.com/1052693
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53116}