port 64e3bad3 (r30577)

original commit message:

    This is uncontroversial the dead code removal part of
    https://codereview.chromium.org/1307943013, which was
    previously landed, but got reverted because of DOM
    breakage that requires more investigation.

BUG=

Review URL: https://codereview.chromium.org/1321653004

Cr-Commit-Position: refs/heads/master@{#30611}