Not using the atlas feature on web breaks rendering

[deifactor]

If I run the examples in my browser without enabling the atlas feature, tiles generally either don't render or render completely wrong. Based on my experimentation in my own codebase, It seems like any tile with TileTextureIndex(0) will instead render the last tile, and any other index will fail to render.

If I do use the atlas feature, everything works fine.

[rparrett]

There's an existing issue tracking this here: #283