[BUG] poly2tri reference in babylon imported from npm as modules

Hi,

I recently encountered a small problem when I refactored my project relying on polygon mesh builder using ES6 modules and npm.

If I include babylon js and poly2tri with npm and import it using 
 

import poly2tri from 'poly2tri';
import BABYLON from 'babylonjs';

This way, the poly2tri package is available locally.

So, I get an error saying:

"PolygonMeshBuilder cannot be used because poly2tri is not referenced"

It probably comes from there (babylon.polygonMesh.ts):

if (!("poly2tri" in window)) {
    throw "PolygonMeshBuilder cannot be used because poly2tri is not referenced";
}

So, I'm forced to do the following before using PolygonMeshBuilder (which is not a very good way to go IMO):

window.poly2tri = poly2tri;

Shouldn't it be:

if (!("poly2tri" in window || polytri)) {
    throw "PolygonMeshBuilder cannot be used because poly2tri is not referenced";
}

EDIT: Sorry, I put this in the wrong place, and I can't delete it neither move it.