Bring 2.0 stroke ordering fixes to 1.x

[davepagurek]

Resolves #6386 for 1.x

We noticed that this sketch https://editor.p5js.org/davepagurek/sketches/yohhELoPC works on Mac but not Windows, where strokes don't render and just appear blank. @Stefterv narrowed it down to a change in 1.10.0 (it works in 1.9.4) and that it also works in 2.0.

I realized that this was fixed in 2.0 in #7369 (we also were adding more visual tests and were noticing that some stroke ones regularly fail on Windows) but that the same changes never made it to 1.11.x. This PR git cherry-picks that PR onto the main branch to get the same changes.

There's more context in the comments of that PR, but the main problem is that an earlier change picked a small number that happened to rely on rounding that only happened on Macs, leaving Windows broken by accident. A later change (#7206) made it so that we can just turn that small negative number to 0 and avoid the Windows issues. You'll also see in the diff that the precision was bumped to high to fix discrepancies on mobile too (desktop basically always ignores the precision and uses high, but mobile will treat it differently, which in this case would cause similar visual bugs.)

https://editor.p5js.org/davepagurek/sketches/yohhELoPC now uses a custom p5 build to test the changes.

[davepagurek]

@Stefterv doule-checked for me that the sketch works on Windows again so I'm going to merge this in to make the shaders the same again on 2.0/1.x!