Returns a silent audio track, cloned off a shared AudioContext created on first use. Hand the
clone back to releaseEmptyAudioStreamTrack rather than stopping it, so the context can close.
A clone that is only stopped stays counted as outstanding, which holds the shared context open
for the lifetime of the page.
Returns a silent audio track, cloned off a shared
AudioContextcreated on first use. Hand the clone back toreleaseEmptyAudioStreamTrackrather than stopping it, so the context can close. A clone that is only stopped stays counted as outstanding, which holds the shared context open for the lifetime of the page.