Revert of Send Windows accessibility events based on tree updates.

Revert of Send Windows accessibility events based on tree updates. (patchset #9 id:160001 of https://codereview.chromium.org/848653002/)

Reason for revert:
DumpAccessibilityEventsTest.AccessibilityEventsTextChanged failing frequently on Windows bots.  Fails most of the time on Win8 Aura.

Original issue's description:
> Send Windows accessibility events based on tree updates.
>
> The idea of this change is to fire Win AX events
> based on the AX tree changing, rather than based
> on Blink firing the right event and mapping it to a
> Win event.
>
> Store the Win-specific AX attributes (ia role,
> ia state, name, value, etc.) in a struct, and when a
> node is updated, compare the old value of each attribute
> to the new value and fire an appropriate event for each
> one (name changed, state changed, etc.).
>
> Handle hypertext_ similarly, and properly diff the old and new hypertext in get_oldText and get_newText.
>
> This enables all of the "event" tests that were
> previously added to pass now, and it makes live regions
> work correctly in NVDA and JAWS.
>
> BUG=447962
>
> Committed: https://crrev.com/eb691a960bef3c2aefa38627baa7cbdde480b81e
> Cr-Commit-Position: refs/heads/master@{#313052}

TBR=dtseng@chromium.org,aboxhall@chromium.org,dmazzoni@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=447962
Committed: https://crrev.com/9ddab275f9681cfdef2aa1ed5b8c3d9431b58468
Cr-Commit-Position: refs/heads/master@{#313067}

[pauljensen, 2015-01-26 14:57:00]

Created Revert of Send Windows accessibility events based on tree updates.

[commit-bot: I haz the power, 2015-01-26 14:58:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/880523002/1

[commit-bot: I haz the power, 2015-01-26 14:58:51]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-26 15:00:04]

Patchset 1 (id:??) landed as
https://crrev.com/9ddab275f9681cfdef2aa1ed5b8c3d9431b58468
Cr-Commit-Position: refs/heads/master@{#313067}