[tomjakubowski]

I believe that, in WebGL, if you sample the texture in a shader the resulting color is in a linear space. And output colors from a fragment shader are meant to be linear as well.

I realize now that I can't fully answer your question, because I'm unsure whether WebGL implementations are supposed to respect color correction information in the image file format. But I'm pretty sure that the color space in WebGL "shader land" is always linear.