Previously we wouldn't respect font-variation-settings for fonts matched
through `font_matching_algorithm` (i.e. any fonts which didn't have an
exact loaded match).
The text track processing model would previously spin forever waiting
for the track URL to change. It would then recursively invoke itself
to handle the new URL, again entering the spin loop. This meant that
tracks could easily cause event loop hangs.
We now have an observer system to be notified when the track state
changes instead. This lets us exit the processing model and move on.
The video was accidentally removed in commit d5ba665f89.
This adds the video back to the LibWeb/Text/data folder, and validates
that the video loads in the test that depends on it loading.
