Handle double precision in playState

[johannesodland]

Double precision errors can prevent playState from becoming "finished",
which in turn prevents the finished promise from resolving.

This is caused by precision loss due to floating point computations. For instance, converting an internal holdTime of 100000 to CSSNumberish and back can cause currentTime to become 99999.99999999999.

When the imprecise currentTime is compared against the effectEnd() with a regular >= operator the comparison will fail. This PR introduces an epsilon check to address this and ensure that the playState can become "finished".

[porfirioribeiro]

This may be the reason why sometimes my timelines never finish!