to target pane, which already has all the needed props.

Should help with smaller screen sizes, where the ratio is different (like some chromebooks)

It claims to support other sample rates, as the spec requires, but it
does not.

* Added object.assign polyfill

* Fix IE load failure

Don’t call `(window.AudioContext || window.webkitAudioContext)()` if platform is IE

Catch any other errors, and display Browser unsupported in error-boundary.

If for some reason there are no other errors (unlikely), preview-modal will still check for IE and show the unsupported modal.

Polyfilling Object.assign is enough to get through load and show the modal for IE. We can always switch to `babel-polyfill` if there are others needed later, but for now this is smaller.

Add Error Boundary (has componentDidCatch method) to handle WebGL errors and display an informative message. 

* Update libraries re: feedback. Resolves GH-1182 GH-1187 GH-1188 GH-1189 GH-1184

* Rename astronaut in space theme

* Change default variable name to 'my variable'. 

* Update integration test to look for 'my variable'. Re GH-1162

* Resolve issue with space in integration test

Update opcode label for monitors.

* Add coming soon extensions to the library

This implements #1074

* don’t call `onSelect` when disabled

thanks @paulkaplan!

* add speech image to coming soon extension