Revert commit# 415577 "Add grid/flex layout support for <fieldset>"
This patch partially reverts crrev.com/415577.
Reason for revert: Broke real world websites.
BUG=
670837
NOTRY=true
NOPRESUBMIT=true
Review-Url:
https://codereview.chromium.org/2549973003
Cr-Commit-Position: refs/heads/master@{#436992}