copyInto
Converts frame to RGBA and copies it into destination.
Return
false when this frame cannot be drawn: it carries no picture, the RGBA format is not in this build, the conversion failed, or destination is the wrong size. False is not an error here. A renderer answers the engine's present with it, the schedule counts a drop, and playback carries on, which is what the renderer contract asks for.
Parameters
destination
a JS Uint8ClampedArray or Uint8Array whose length is exactly width times height times four. An ImageData.data is the intended argument.