Currently we have a few WebGL performance tests on the perf bots, but they are quite limited.

1) They don't cover WebGL2 APIs at all
2) They probably don't cover less common context configs, say alpha{true|false}, preserveDrawingBuffer{true|false}, premultiplyAlpha{true|false}.

While it is extremely difficult to come up with a good set of perf matrix for graphics performance, we should probably select a bunch of demos doing different things, and putting them onto perf bots.