This makes it possible for handles.h to #include objects.h, which
upcoming changes will need.

Bug: v8:3770
Change-Id: I4f500736028668749bb73fb24f9732df757e97d0
Reviewed-on: https://chromium-review.googlesource.com/c/1278487Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56615}