Add support for AtkComponent scrolling APIs

Bug: 932708
Change-Id: Ib793df737907234c4ffe7f7d7f591086711d9f81
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1574721
Commit-Queue: Martin Robinson <mrobinson@igalia.com>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652882}
10 files changed