`HTMLCanvasElement.captureStream()` prompts us to imagine uses of `HTMLMapElement.captureStream()`

[prushforth]

Seeing HTMLCanvasElement.captureStream() made me think that an HTMLMapElement.captureStream() could be defined to capture the contents of a <map> element at an efficient frame rate. It makes me think we may have removed references to media element in the spec a little too hastily, but eh. There's room to work in :-)

Such an API could have potential for map whiteboard sharing, and other use cases TBD.