Not my real area of expertise, but just looking at the test I see two warning signs:

- It uses async_test instead of promise_test. That means all the tests in that file run concurrently instead of one after the other, so they could potentially be interfering with each other.
- It is attempting to trigger a series of animation events based on CSS stuff. I don't know if there's a better way, but I could indeed see this going wrong somehow. Maybe the animations team can help.

I'll CC the test author (from Gecko) in case he has ideas.

Could anyone help remove my @upsuper.org account from this issue? I don't have a Google account on that address.

All the subtests in that test use an independent element, so I don't see how that could go wrong from the perspective of the spec.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/981ff3850e661dae2425f4183aeb1dc8c1104d19

commit 981ff3850e661dae2425f4183aeb1dc8c1104d19
Author: qyearsley <qyearsley@chromium.org>
Date: Wed Mar 15 00:59:00 2017

Add flaky timeout expectation for external/wpt/dom/events/EventListener-invoke-legacy.html

BUG= 701445 

Review-Url: https://codereview.chromium.org/2753693002
Cr-Commit-Position: refs/heads/master@{#456928}

[modify] https://crrev.com/981ff3850e661dae2425f4183aeb1dc8c1104d19/third_party/WebKit/LayoutTests/TestExpectations

Remove Blink>DOM>Events

So, Gecko actually has the same issue with this test. See https://bugzilla.mozilla.org/show_bug.cgi?id=1351409

I just figured out that this is because the animationiteration event is not guaranteed to be fired, and thus this test can intermittently wait on that event forever.

In the aforementioned Gecko bug, I've submitted a patch to remove animationiteration from the test to make it work reliably. When that gets synced to chromium, you may want to update the expectation here as well.

Since the WPT is fixed, I'm going to update the test expectation for this test.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4f333e03adcfbba3812bc85a1eca5a081b441974

commit 4f333e03adcfbba3812bc85a1eca5a081b441974
Author: Rakina Zata Amni <rakina@chromium.org>
Date: Mon Jan 15 07:45:37 2018

Remove timeout expectation for EventListener-invoke-legacy.html

wpt/dom/events/EventListener-invoke-legacy.html previously flakily times
out,  but the WPT is now fixed (by Mozilla). This CL removes timeout
expectation for the test.

Bug:  701445 
Change-Id: I23fee21356b745a6affc629e7c9ae37cc618cbb3
Reviewed-on: https://chromium-review.googlesource.com/866283
Reviewed-by: Takayoshi Kochi <kochi@chromium.org>
Commit-Queue: Rakina Zata Amni <rakina@chromium.org>
Cr-Commit-Position: refs/heads/master@{#529223}
[modify] https://crrev.com/4f333e03adcfbba3812bc85a1eca5a081b441974/third_party/WebKit/LayoutTests/TestExpectations