Removes
- SequentialMarkingDeque
- The ability to handle marking deque overflow
- BlackToGrey transitions

We switched to a different marking work list on M61 that fails
in OOM upon failing to allocate Segments used in the work list.

Bug: chromium:758570
Change-Id: I66e2ab912271bf84b085dccc9b4bdd96076b64fb
Reviewed-on: https://chromium-review.googlesource.com/632676
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48078}