A google search would show all sorts of people using multiple render targets (aka MRT) with the WEBGL_draw_buffers extension. The search would also show that both Firefox and Chrome are supposedly supporting it, and that one might have to enable a flag in about:config / about:flags respectively that would allow the usage of extensions that are still in draft status.
However, none of the above gave me access to the extension. I changed the configuration on both Firefox Aurora and Chrome Canary, and no luck.
Is there any solution?