Adding support for ARIA 1.1 role="none"

In ARIA 1.1, the working group plans to introduce 'none' as a synonym to the 'presentation' role,
due to author confusion surrounding the intended meaning of the word "presentation" or "presentational."
Many individuals erroneously consider role="presentation" to be synonymous with aria-hidden="true",
and we believe role="none" conveys the actual meaning more unambiguously.

After considerable time, aria role presentation would be deprecated out.

BUG=385070

Review URL: https://codereview.chromium.org/588653003

git-svn-id: svn://svn.chromium.org/blink/trunk@182472 bbb929c8-8fbe-4397-9dbb-9b2b20218538