Basemark has just released Basemark Web 3.0, which includes WebGL 2.0 tests for supporting browsers. No browsers support the standard by default yet, although it can be enabled on Firefox and Chrome with a command-line flag.
WebGL 1.0 has become ubiquitous, but it is based on quite an old version of OpenGL. OpenGL ES 2.0 was specified all the way back in March 2007. While it simplified development by forcing everyone down a programmable shader pipeline, it has quite a few limitations. OpenGL ES 3.0 remedied many of these, such as allowing multiple render targets and texture compression. OpenGL ES 3.1 added compute shaders, which brings us pretty much to today. In fact, Vulkan targets OpenGL ES 3.1 hardware (should the hardware vendor provide a driver).
WebGL targeted OpenGL ES 2.0. WebGL 2 targets OpenGL ES 3.0.
Of course, this means that the WebGL 2.0 base standard does not support compute shaders, which is a bit of a drag. It's something that they really want to incorporate, though, but they still can't seem to decide whether it will align with a new version of WebGL (such as WebGL 2.1) or be incorporated in a multi-vendor extension.
So where are we today?
Well, WebGL 2.0 is still a little ways off from being everywhere. As we mentioned, only Firefox and Chrome support the standard, although WebKit is working on it, too. Microsoft has WebGL 2.0 listed as “Under Consideration” with a “Roadmap Priority” of Medium, “Development is likely for a future release.” One major hold up was its shader support. Again, OpenGL ES 3.0 shaders are much more complex than OpenGL ES 2.0 ones, and many WebGL browsers convert OpenGL ES 2.0 shaders to HLSL for DirectX on Windows. This circumvents lackluster graphics drivers, and it adds an extra, huge layer of complexity for someone who wants to write malware. It's not sufficient to know of a driver bug with a specific shader string — you need to trick the transpiler into outputting it, too.
But, again, we're slowly inching our way there.