pathLength does not affect percentage calculations

[ewilligers]

When values like startOffset are expressed as percentages,
pathLength has no effect. This includes when pathLength is 0.

resolves #383

[css-meeting-bot]

The Working Group just discussed pathLength PR.

The full IRC log of that discussion

<AmeliaBR> Topic: pathLength PR
<AmeliaBR> gitHub: https://github.com//pull/485
<liam> [are we on 485 or https://github.com//issues/383 ? ]
<liam> AmeliaBR, in most cases differences in path length adjustment will cancel out, but we have a special rule about handling path length of zero
<liam> and for a +ve length you go to the end of the path instead of the beginning
<liam> so the only change is to say that doesn't affect MISSED
<liam> Eric: any +ve non-% length goes to the end of the path
<AmeliaBR> s/MISSED/percentage length values/
<liam> Dirk: if that's implemnt behaviour it's fine with be
<liam> AmeliaBR: Eric - are there tests for the changes?
<liam> Eric: there were non-percent path lengths,haven't done zero with % but i'll add them now
<liam> AmeliaBR: need a review, ok with me
<ericwilligers> Any positive non-percentage lengths goes to the end of the path.
<liam> Eric: new proposal (see preceding IRC line)
<ericwilligers> Percentages resolve to 0 when pathLength is 0
<liam> Dirk: for 0 you'd get the end of the path but percentages resolve to zero
<ericwilligers> 0 is always the start of the path.
<liam> AmeliaBR: these are all edge cases anyway
<liam> Eric: I'll send a new pr and tests.
<ericwilligers> https://github.com//issues/484