WebCL community is geared towards exposing platform OpenCL backed by GPU, that would be stealing their fire.
Though it might still be the smartest thing to do given the poor state and lack of recent progress of GPU OpenCL drivers. Even desktop apps that would like to use OpenCL are just barely limping along. See eg. Blender.
I agree, even CPU implementation of WebCL could be much faster, than the fastest JS engine (because it is low-level C code). Currently there are several very good OpenCL implementations, running on the CPU.
Though it might still be the smartest thing to do given the poor state and lack of recent progress of GPU OpenCL drivers. Even desktop apps that would like to use OpenCL are just barely limping along. See eg. Blender.