Migrate hypertext support APIs from BrowserAccessiblity to AXPlatformNode

This brings over the support for IA2 hyperlinks and selection from
BrowserAccessiblity to AXPlatformNode.  The next step will be to
move the MSCOM facing APIs over to the AXPlatformNode (IAccessibleText).

Bug: 703369
Change-Id: I5dc3ef1ad6292947eab50e0dd22586f87d171960
Reviewed-on: https://chromium-review.googlesource.com/639027
Commit-Queue: Doug Turner <dougt@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#500226}
6 files changed