[WEB] a texture for writing SH coefficients to
[WEB] a texture for writing SH coefficients to

Here is the plan:

The rgb channels of the 8 pixels will hold, respectively, the
spherical harmonic coefficient terms:

L(1,-1)
L(1,0)
L(1,1)
L(2,-2)
L(2,-1)
L(2,0)
L(2,1)
L(2,2)

The alpha channels of the first 3 pixels will hold, respectively,
the rgb of the spherical harmonic term L(0,0)

This is probably terrible, but it's the best solution I can come
up with right now.

davidyu/Robinson,davidyu/Robinson,davidyu/Robinson