Degenerate triangle sleeves run across screen

[kkaefer]

Currently, when rendering into the stencil buffer, we're seeing lots of pointy degenerate(?) triangles running all over the screen:

Instead, they should look like triangle fans that are limited to the bounding box of the feature. Since iOS is using a tiled GL renderer, we should reduce the sleeves that run across the screen (which aren't visible anyway) so that we don't need to process all of the tiles.

[kkaefer]

This is now gone because we don't do any degenerate stuff anymore.