They try to synthesize `mouseover` which is mapped to `eMouseEnterIntoWidget`
internal event (which is not same as DOM `mouseover`) after `click`. However,
with any pointing devices, `mousemove` should occur before `mousedown`.
Therefore, in the real world, `mouseover` should be fired before `mousedown`,
`mouseup` and `click` in the test. Therefore, this swaps the event order.
Note that after fixing bug 1914546, `mouseover` will be fired immediately after
`mouseup` and `click`. This makes the test waits `mouseover` after it's fired.
So, it'd permanently timeout after the fix.
Differential Revision: https://phabricator.services.mozilla.com/D220839
aa8485f065