UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.181 Safari/537.36

Steps to reproduce the problem:
1. Go to https://codepen.io/monfera/pen/RyXmjL
2. Observe that, every few seconds, the gray painted area is suddenly enlarged (for me, it's happening on the right hand side), as if it tried to encircle all points on the right
3. 

What is the expected behavior?
Although it's quite a bit of stress testing in terms of polygon self-intersections, I believe it shouldn't yield these blinks.  I see blinking at as low as `var n = 500` (see the first JS row) but, since the rAF loop is faster, the blink is more transient, harder to notice. Setting `fill-opacity` of the `polyline` to 1 in CSS makes the blinking more prominent.

What went wrong?
See the attached MP4: blinking is prominent on my machine(TM)

Did this work before? Yes I don't know, but I didn't notice it when creating it the original of this fork maybe a couple of years back

Does this work in other browsers? No
 The issue is present in Safari.
FireFox doesn't have this glitch.

Chrome version: 66.0.3359.181  Channel: stable
OS Version: OS X 10.13.4
Flash Version: 

Probably completely unrelated to https://bugs.chromium.org/p/chromium/issues/detail?id=844998
 

Deleted: blink.mp4 9.2 MB

	blink.mp4 9.2 MB View Download