Implement support for new blockquote, caption, and paragraph ARIA roles

These three roles are part of reaching role parity with HTML5. As such,
they should be exposed via platform accessibility APIs in the same way
as their native host language counterparts. Thus just add them to the
map of ARIA roles to internal roles.

Bug: 849650
Change-Id: I9a513e187a5beccd57fc5c7306929b0fd194b6dd
Reviewed-on: https://chromium-review.googlesource.com/1169476
Commit-Queue: Nektarios Paisios <nektar@chromium.org>
Reviewed-by: Nektarios Paisios <nektar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582340}
21 files changed