function isKeypressCommand(nativeEvent) {
  return (
    (nativeEvent.ctrlKey || nativeEvent.altKey || nativeEvent.metaKey) &&
    // ctrlKey && altKey is equivalent to AltGr, and is not a command.
    !(nativeEvent.ctrlKey && nativeEvent.altKey)
  );
}
If native `textInput` events are available, our goal is to make
use of them. However, there is a special case: the spacebar key.
In Webkit, preventing default on a spacebar `textInput` event
cancels character insertion, but it *also* causes the browser
to fall back to its default spacebar behavior of scrolling the
page.

Tracking at:
https://code.google.com/p/chromium/issues/detail?id=355103

To avoid this issue, use the keypress event as if no `textInput`
event is available.