Enable WEBGL_depth_texture on GL context init. WEBGL_depth_texture is an extension that adds support for 16-bit and 32-bit integer depth formats, as well as the packed d24s8 integer depth+stencil format. See http://www.khronos.org/registry/webgl/extensions/WEBGL_depth_texture/
Fix indentation in previous commit.
Merge pull request #1658 from juj/WEBGL_depth_texture

Webgl depth texture