SuspendGenerator needs the accumulator to be live so that it can return
it.

Bug: chromium:806723
Change-Id: Iaa88fce96c36876e3e4256324ca650d475480c10
Reviewed-on: https://chromium-review.googlesource.com/975404Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52147}