voronoi.polygons crashes (runs out of memory)

[yagebu]

Hey, thanks for d3 and all its various great packages!

We (see beancount/fava#731) recently in an out of memory issue with one of the charts of Fava - a line chart (looking like this) using a voronoi diagram to provide tooltips. A call to voronoi.polygons() seemed to be the culprit and the following snippet on runkit seems to reproduce the error (it crashes with error code 137, which denotes 'out of memory' afaict): https://runkit.com/yagebu/5ac88e13ef4e310012a3c15f

[Fil]

I have reproduced the problem in an observable and the browser intercepted the error beofre the crash, and threw me in the debugger, which in turns gave a nice view of the state:

[Fil]

The solution is to reimplement with d3-delaunay, as you did in beancount/fava#779