This reverts commit 081ad5e9f15e8b6e7c6cafe9ba408988b6e78bdc.

Reason for revert:

Findit (https://goo.gl/kROfz5) identified CL at revision 641316 as the
culprit for flakes in the build cycles as shown on:
https://analysis.chromium.org/p/chromium/flake-portal/analysis/culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyQwsSDEZsYWtlQ3VscHJpdCIxY2hyb21pdW0vMDgxYWQ1ZTlmMTVlOGI2ZTdjNmNhZmU5YmE0MDg5ODhiNmU3OGJkYww

Sample Failed Build: https://ci.chromium.org/buildbot/chromium.linux/Linux%20Tests%20%28dbg%29%281%29/78993

Sample Failed Step: webkit_layout_tests

Sample Flaky Test: virtual/mouseevent_fractional/fast/events/pointerevents/mouse-pointer-capture-in-iframe.html

Original change's description:
> Reland "Make pointer capture work in same origin frame"
>
> This is a reland of d44248f2a896421c1382c1dbbf0d7e1a9b798470
>
> Original change is reverted by findit due to test flaky.
> The flaky test is:
> fast/events/pointerevents/mouse-pointer-capture-in-iframe.html
>
> This is reland with fixing tests.
>
> Original change's description:
> > Make pointer capture work in same origin frame
> >
> > We used to send mouse event to the subframe before apply the pointer
> > capture target, and it causes the pointer capture doesn't work when
> > capture to a outer frame target and move to inner frame.
> >
> > This CL changes three things:
> > 1. 'Rename' the |capturing_mouse_events_element_| to
> > |capturing_subframe_element_| as it only used for the frame capture
> > (There is plan to remove the frame capture logic once we have pointer
> > capture work correctly)
> > 2. On HandleMouse*Event, instead of always perform a hit test, we use
> > either frame capture target or pointer capture target to re-construct
> > the HitTestResult.
> > 3. When using the capture target, update the hover active state for
> > capture target.
> >
> > This change makes captured pointer event sent correctly when over
> > same origin frame, and also decrease the hit_test_count because of
> > frame capturing.
> >
> > Note that after this change, we still NOT allow set/release pointer
> > capture across same-origin frame as the pointer id and active statue
> > is per frame.
> >
> > See design doc:
> > https://docs.google.com/document/d/1cOZu98UuKk5bdARUQKmj2Q8YoEMpd9l78T0k-cf5ttc/
> >
> > This change is under a blink flag UnifiedPointerCaptureInBlink.
> >
> > Change-Id: I61c6a02086535d2a145df9d414df0bdc9673101e
> > Bug: 936190, 919908
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1446556
> > Commit-Queue: Ella Ge <eirage@chromium.org>
> > Reviewed-by: Navid Zolghadr <nzolghadr@chromium.org>
> > Reviewed-by: David Bokan <bokan@chromium.org>
> > Reviewed-by: Mustaq Ahmed <mustaq@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#640055}
>
> Bug: 936190, 919908
> Change-Id: Icc374c16b1aee0b9125593801c8787f28c7db554
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1520941
> Reviewed-by: David Bokan <bokan@chromium.org>
> Reviewed-by: Navid Zolghadr <nzolghadr@chromium.org>
> Reviewed-by: Mustaq Ahmed <mustaq@chromium.org>
> Commit-Queue: Ella Ge <eirage@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#641316}

Change-Id: I9fb0a95a8736bbb22c8c7e247b00cf3263820f76
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 936190, 919908