GitLab

1. Updating functionality of `ITextRangeProvider::MoveEndpointByUnit` to
   reflect UIA-specific behavior expected by ATs when moving by line and
   crossing the start of an inline block boundary, which should be
   effectively treated as a line break.

   This is mostly implemented in `AXPlatformNodeTextRangeProviderWin`,
   but a new method `AtStartOfInlineBlock` is introduced in `AXPosition`
   to expose inline block boundaries similar to how paragraph boundaries
   are computed by using an `AbortMovePredicate`.

2. Adding browser tests to cover new expectations mentioned above.

Bug: 928948
Change-Id: Ie243a96885edaf3037c75f375ae4fce20fa29e30
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1858518
Commit-Queue: Kurt Catti-Schmidt <kschmi@microsoft.com>
Reviewed-by: Kurt Catti-Schmidt <kschmi@microsoft.com>
Reviewed-by: Nektarios Paisios <nektar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709093}