Testing CSS caret-animation is challenging

[schenney-chromium]

The CSS caret-animation property controls caret blinking behavior, but different platforms blink at different rates, and the timing of the test can impact the exact time the caret starts to blink. It is then very hard to write tests that pass on all platforms and are not flaky.

Maybe it is possible to add js hooks to test this feature reliably, although in practice it will never be possible to test the real browser behavior (similar to spell checking testing, for example).