Fix OBJ index buffer for webgl
Fix OBJ index buffer for webgl

I'm pretty surprised this worked on desktop, but I guess a buffer is a
buffer and since it's C it doesn't do any hand-holding for me. The issue
was that I mistakenly bound the index buffer as an ARRAY_BUFFER rather
than an ELEMENT_ARRAY_BUFFER. Standard OpenGL evidently doesn't care,
but WebGL was unhappy when I later tried to bind the same buffer as an
ELEMENT_ARRAY_BUFFER.

Omustardo/gome