I did a quick pass through all "intermittent *-print.html" WPT test-failures that have been filed in the past ~6 months December, and they're all unexpected timeouts, likely due to this issue. I added them as dependencies of this bug. (Many of them have been closed as INCOMPLETE, probably because this issue isn't test-specific; it affects all print tests to an equal extent, I imagine, with some amount of mysterious delay that's only flagged as a test failure if it happens to overshoot 10s which it occasionally does.)
Bug 1886588 Comment 2 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
I did a quick pass through all "intermittent *-print.html" WPT test-failures that have been filed in the past ~6 months (since December), and they're all unexpected timeouts, likely due to this issue. I added them as dependencies of this bug. (Many of them have been closed as INCOMPLETE, probably because this issue isn't test-specific; it affects all print tests to an equal extent, I imagine, with some amount of mysterious delay that's only flagged as a test failure if it happens to overshoot 10s which it occasionally does.)