Given the use of the epsilon, this is pretty specific.  This could use a new name like `splitTriangleAtInternationalDateLine`.

Since this is specific, it probably belongs as a file-level scope function in PolygonPipeline.js, in which case you don't have to worry about doc.

Also, when I originally wrote `wrapLongitude`, I think I thought that I would merge a function like this right into it or at least more tightly couple them, which would clean up the index conversion starting at
```
// Replace triangle that crosses the IDL with three
// triangles that do not cross.
```
@bagnell thoughts?