Revert of Introduce SynchronousMutationObserver::didChangeAttribute()

Revert of Introduce SynchronousMutationObserver::didChangeAttribute() (patchset #3 id:60001 of https://codereview.chromium.org/2641803003/ )

Reason for revert:
Performance regression on blink_perf.dom: modify-element-title/modify-element-title

http://crbug.com/684394

Original issue's description:
> Introduce SynchronousMutationObserver::didChangeAttribute()
> 
> This patch introduces |SynchronousMutationObserver::didChangeAttribute()| to
> observe attribute changes in |Element| for a preparation of [1] which tracks
> attribute changes for invalidating cached |VisibleSelection|.
> 
> [1] http://crrev.com/2637013002: Make FrameSelection to hold non-canonicalized
> positions
> 
> BUG=682878
> TEST=run_webkit_unitetests --gtest_filter=DocumentTest.SynchronousMutationNotifierChangeAttribute)
> 
> Review-Url: https://codereview.chromium.org/2641803003
> Cr-Commit-Position: refs/heads/master@{#445006}
> Committed: https://chromium.googlesource.com/chromium/src/+/f34f5cb8f4f2f4a54afe4094dc7933193220116e

TBR=tkent@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=682878
Review-Url: https://codereview.chromium.org/2650353002
Cr-Commit-Position: refs/heads/master@{#445929}
Committed: https://chromium.googlesource.com/chromium/src/+/eb6e1f0d57a18e16ffa21254bf954610112f858b

[yosin_UTC9, 2017-01-25 01:30:34]

The CQ bit was checked by yosin@chromium.org

[yosin_UTC9, 2017-01-25 01:30:34]

Created Revert of Introduce SynchronousMutationObserver::didChangeAttribute()

[commit-bot: I haz the power, 2017-01-25 01:31:27]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[tkent, 2017-01-25 01:37:21]

lgtm

[commit-bot: I haz the power, 2017-01-25 03:23:52]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1485307834398490, "parent_rev":
"7011986566d75140d56f66ae98129acbb9196a0d", "commit_rev":
"eb6e1f0d57a18e16ffa21254bf954610112f858b"}

[commit-bot: I haz the power, 2017-01-25 03:24:22]

Description was changed from

==========
Revert of Introduce SynchronousMutationObserver::didChangeAttribute() (patchset
#3 id:60001 of https://codereview.chromium.org/2641803003/ )

Reason for revert:
Performance regression on blink_perf.dom:
modify-element-title/modify-element-title

http://crbug.com/684394

Original issue's description:
> Introduce SynchronousMutationObserver::didChangeAttribute()
> 
> This patch introduces |SynchronousMutationObserver::didChangeAttribute()| to
> observe attribute changes in |Element| for a preparation of [1] which tracks
> attribute changes for invalidating cached |VisibleSelection|.
> 
> [1] http://crrev.com/2637013002: Make FrameSelection to hold non-canonicalized
> positions
> 
> BUG=682878
> TEST=run_webkit_unitetests
--gtest_filter=DocumentTest.SynchronousMutationNotifierChangeAttribute)
> 
> Review-Url: https://codereview.chromium.org/2641803003
> Cr-Commit-Position: refs/heads/master@{#445006}
> Committed:
https://chromium.googlesource.com/chromium/src/+/f34f5cb8f4f2f4a54afe4094dc79...

TBR=tkent@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=682878
==========

to

==========
Revert of Introduce SynchronousMutationObserver::didChangeAttribute() (patchset
#3 id:60001 of https://codereview.chromium.org/2641803003/ )

Reason for revert:
Performance regression on blink_perf.dom:
modify-element-title/modify-element-title

http://crbug.com/684394

Original issue's description:
> Introduce SynchronousMutationObserver::didChangeAttribute()
> 
> This patch introduces |SynchronousMutationObserver::didChangeAttribute()| to
> observe attribute changes in |Element| for a preparation of [1] which tracks
> attribute changes for invalidating cached |VisibleSelection|.
> 
> [1] http://crrev.com/2637013002: Make FrameSelection to hold non-canonicalized
> positions
> 
> BUG=682878
> TEST=run_webkit_unitetests
--gtest_filter=DocumentTest.SynchronousMutationNotifierChangeAttribute)
> 
> Review-Url: https://codereview.chromium.org/2641803003
> Cr-Commit-Position: refs/heads/master@{#445006}
> Committed:
https://chromium.googlesource.com/chromium/src/+/f34f5cb8f4f2f4a54afe4094dc79...

TBR=tkent@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=682878

Review-Url: https://codereview.chromium.org/2650353002
Cr-Commit-Position: refs/heads/master@{#445929}
Committed:
https://chromium.googlesource.com/chromium/src/+/eb6e1f0d57a18e16ffa21254bf95...
==========

[commit-bot: I haz the power, 2017-01-25 03:24:23]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/eb6e1f0d57a18e16ffa21254bf95...