In an embedded handler build, it's not guaranteed that every handler
is embedded (and thus immovable). The GC must still iterate the
dispatch table to update pointers to moved code objects.

TBR=rmcilroy@chromium.org

Bug: v8:8068
Change-Id: I8b37f1758fdc670081e0c4f58795aea271811994
Reviewed-on: https://chromium-review.googlesource.com/1238236Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56148}