Port 64e3bad3

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.

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1311123004

Cr-Commit-Position: refs/heads/master@{#30590}