We should draw polygons by tesselating them instead of using the stencil buffer trick. Native already does this. 7b35312 is a first attempt that uses libtess.js. Rendering is faster but the tesselation is slow. The buildings layer can take up to 500ms to tesselate.

• take a look at poly2tri.js (which only accepts simple polygons)
• revisit tesselating polygons in the tiles