This patch removes creation of fillers in the middle of a large page and
fixes assert in Heap::NotifyObjectLayoutChange.

The fillers in large pages are useless since we do not sweep large
object space.

Bug: chromium:752426
Change-Id: I01c230223f28d6d54b7362ee70e9d83de50678fd
Reviewed-on: https://chromium-review.googlesource.com/601994
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47221}