Bluetooth.requestDevice doesn't work from a cross origin iframe

When playing around with the Muse EEG headset, @teonbrooks noticed that you can't call [Bluetooth.requestDevice](https://developer.mozilla.org/en-US/docs/Web/API/Bluetooth/requestDevice) from a cross origin iframe (presumably for security reasons).

I guess we'll need a message passing solution to/from the editor frame to make this work.

(Can still proceed using the local server where things are on the same domain, though).