Real, deterministic Web Audio (it used to be a silent stub)

OfflineAudioContext - the API a page uses to synthesise or process sound and read the resulting samples - used to be a stub that returned silence. It now genuinely renders. An audio graph of oscillators, gain, constant sources and buffer sources is evaluated block by block into real samples, and because the render is a pure function of the graph it is bit-exact and reproducible on every machine, which is a property the reference implementations do not guarantee. The Media figure moves for a whole subsystem going from nothing to real.