Correct alignment in ContiguousContainer::appendByMoving()

CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
BUG=625381
TBR=enne@chromium.org (for same change in cc as in blink)

Review-Url: https://codereview.chromium.org/2122573002
Cr-Commit-Position: refs/heads/master@{#403979}
4 files changed