WPT coverage of the tests of event-timing at the revision 5602b0f210e3. The tests link to their results in the browsers on wpt.fyi. The tentative tests (experimental features) and the reftests are listed separately from the stable tests.
there is no fling: a touch pan scrolls instantly and ends when the touch is released, so the second tap stops nothing and is an interaction (its pointerdown has an interactionId, the test expects 0; the first pointerdown, canceled by the pan, has 0). Chrome fails the same assertion on wpt.fyi
the pending event timing entries are not dispatched when the document becomes hidden (the specification only dispatches them in the rendering updates; the browsers end the duration of the events when the page is hidden): the duration of pointerup ends at the rendering update that follows, after minimize() has resolved, so startTime + duration is later than the time the test reads after the visibility change (the runner hides the window in about 1 ms, less than the 8 ms granularity of the duration)
alert() returns at once (no modal dialog is shown), so the duration of the click entry ends at the rendering update that follows the listener instead of when the dialog is shown (startTime + duration is after processingEnd); this end point is not in the specification, and the test is an ERROR (unexpected alert) in Chrome, Firefox and Safari on wpt.fyi
the autoscroll of a selection that the pointer drags past the edge of a scroll container: no scroll event is fired, which the test waits for (it also times out in Chrome and Firefox on wpt.fyi)
the tentative path format of targetSelector (e.g. BODY > DIV:nth-child(1)), which querySelectorAll() must accept: the algorithm of the specification gives IMG[src=/images/green.png] for an image without id, whose attribute value is not quoted (an invalid selector); the 4 other subtests pass (no browser implements targetSelector on wpt.fyi)