Timeline widths can be assigned "NaN%"

[glacials]

If a WSplit run's final split has a finish time of 0 (i.e. the run was never completed) all segments of the timeline chart get a NaN% width.

This is because we obtain the total run time by looking at the final split's finish time. To get each timeline segment's width, we divide that split's duration by the total run time, which gives us a divide-by-zero error in this case.

This only happens for WSplit runs because SplitterZ and TST don't keep track of finish times, only durations, so for those we calculate them manually by summing individual split times.

Example: http://splits.io/F9X3

Pretty colors, but not quite accurate.

The simple fix is to calculate WSplit run times like we do for SplitterZ and TST, instead of depending on that last split's finish time.

However this also brings up an issue of whether or not to display the timeline chart as we currently are for incomplete runs, as its total width doesn't actually represent the duration of the game -- only the total duration of the completed runs. This might be something to think about later.