Clicking AWFY's "Series" drop-down list sometimes auto-selects a menu item instead of opening the drop-down list

[janodvarko]

This is cloned from Bugzilla report: https://bugzilla.mozilla.org/show_bug.cgi?id=1726852

Steps to reproduce

I am testing on Windows 11 Beta.

1. Load https://arewefastyet.com/linux64/cold-page-load/overview?numDays=1
2. Wait for the graphs to load the test results for Firefox, Firefox-Fission, Chrome, and Chromium.
3. Click the "Series" button to open the drop-down list.
4. Click the "Firefox-Fission" menu item.
5. Click the "Clear selection" menu item.
6. Click the page's background once to deselect and close the "Series" drop-down list.
7. Click the page's background a second time to deselect the highlighted "Series" drop-down list button. The "Series" button should change color from grey to white.
8. Click the "Series" button to open the drop-down list.

Expected result

The "Series" drop-down list should open just like it did in step 3.

Actual result

The "Series" drop-down list does not open. Instead the "Firefox" menu item is auto-selected. Sometimes the page will then load the Firefox test results, sometimes it won't load anything.

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See more details in bug 1726852
According to the comment #6, the issue is rather with the page itself.

Honza

[davehunt]

@airimovici could you or someone from the team look into this?