CONSOLE WARNING: 'KeyboardEvent.keyIdentifier' is deprecated and will be removed in M53, around September 2016. See https://www.chromestatus.com/features/5316065118650368 for more details.
  
This tests that DOMKeyboardEvents are created correctly in the JavaScript API.

keydown - key: U+0009@DOM_KEY_LOCATION_STANDARD (keyCode/charCode: 9/0) modifiers: false,false,false,false

keyup - key: U+0009@DOM_KEY_LOCATION_STANDARD (keyCode/charCode: 9/0) modifiers: false,false,true,false