I developed a patch that added the VAO WebGL extensions earlier this year and it's finally out there! So. Cool. And everyone at mozilla is really helpful if you're thinking about contributing for the first time.
Both Django and Rails are very inviting. There's also Plenrt of libraries for many languages that can provide a smaller, more specific place to start (it's often easier if you work with it regularly).
With many projects though, some conflate "my patch was rejected" for "they're jerks" without understanding the impact of their fix/suggestions. Feature bloat, backwards compat, API verbosity, etc all add up.
My understanding is Vertex Array Objects are one of the core browser improvements that asm.js taps into to make C++ based game engines (unreal, rage, unity) crazy fast.
https://developer.mozilla.org/en-US/docs/introduction