concurrent marking is on.

BUG=chromium:694255

Change-Id: I3cd74af9a3f7fb02d982d9366a6a2ebd119a92b2
Reviewed-on: https://chromium-review.googlesource.com/554627Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46324}