This reverts commit a97f76cd07db5041ec7a3665e37c228b1e92f8a0.

Reason for revert:

Findit (https://goo.gl/kROfz5) identified CL at revision 610669 as the
culprit for flakes in the build cycles as shown on:
https://findit-for-me.appspot.com/waterfall/flake/flake-culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyQwsSDEZsYWtlQ3VscHJpdCIxY2hyb21pdW0vYTk3Zjc2Y2QwN2RiNTA0MWVjN2EzNjY1ZTM3YzIyOGIxZTkyZjhhMAw

Sample Failed Build: https://ci.chromium.org/buildbot/chromium.linux/Linux%20Tests%20%28dbg%29%281%29/75936

Sample Failed Step: webkit_layout_tests

Sample Flaky Test: external/wpt/event-timing/event-timing-retrievability.html

Original change's description:
> Move EventTiming tests to WPT
>
> This CL moves the tests in http/tests/event-timing to external/wpt/event-timing.
> The slow image is change from php based to python based. The click is now
> handled by test driver. and setTimeout is replaced with step_timeout.
>
> Bug: 841224
> Change-Id: I035c087550a2d9a67cda1aed88553c16967d04b6
> Reviewed-on: https://chromium-review.googlesource.com/c/1349451
> Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
> Reviewed-by: Timothy Dresser <tdresser@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#610669}

Change-Id: Ia7d9f24fd9866fde7fed255b6b7554e44e4a39ff
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 841224, 908187
Reviewed-on: https://chromium-review.googlesource.com/c/1349500
Cr-Commit-Position: refs/heads/master@{#610689}