Apparently WebCL was blocked by Apple who refused to let their OpenCL patents be used: https://www.khronos.org/files/ip-disclosures/webcl/Apple-Web... ("Apple does not agree to make available .. for any WebCL Specifications")
WebGPU will almost certainly include support for general purpose compute shaders, which pretty much removes the need for a dedicated compute API:
https://docs.google.com/presentation/d/1l1rTCtKHowIEhwzA4l1u...
(besides, building a new API on top of OpenCL would be questionable given that OpenCL is all but dead at this point)
OpenCL is irritating for graphics development, because it doesn't integrate as seamlessly with the rest of the graphics pipeline as GL compute shader does. Unified approaches such as GL compute shader or Vulkan are much more convenient.
Float textures were just optional back in WebGL 1[1]. Any new spec is going to lose in support coverage to WebGL 2 which has been shipping for a year now!
[1] Look for RGBA32F in the WebGL 2 and corresponding OpenGL ES 3.0 specs. Also documented on MDN's coverage of OES_texture_float.
https://www.khronos.org/webcl/