The author may specifiy the unexpected animation-range, e.g. 50% 25%,
and this may cause a negative timeline duration. We have to clamp this
value to avoid the negative duration. Also, now its possible to have
zero duration when normalizing the timing parameters, so removing the
assertion.
Also change the default value in `IntervalForTimelineRangeName()` to be
0 because its type is `nscoord`, instead of `float`. We don't have to
worry about this too much because it is just a temporary solution before
we implement all the range keywords.
Differential Revision: https://phabricator.services.mozilla.com/D288017
Boris Chiou
4654effbfa
