I hadn't seen this written down in documentation anywhere, so I decided to do the obvious and log it out (after looking through source code naively for a bit).

for (var key in TestUtils.Simulate) {
  console.log('key', key);
}

LOG: 'key', 'blur'
LOG: 'key', 'click'
LOG: 'key', 'contextMenu'
LOG: 'key', 'copy'
LOG: 'key', 'cut'
LOG: 'key', 'doubleClick'
LOG: 'key', 'drag'
LOG: 'key', 'dragEnd'
LOG: 'key', 'dragEnter'
LOG: 'key', 'dragExit'
LOG: 'key', 'dragLeave'
LOG: 'key', 'dragOver'
LOG: 'key', 'dragStart'
LOG: 'key', 'drop'
LOG: 'key', 'focus'
LOG: 'key', 'input'
LOG: 'key', 'keyDown'
LOG: 'key', 'keyPress'
LOG: 'key', 'keyUp'
LOG: 'key', 'load'
LOG: 'key', 'error'
LOG: 'key', 'mouseDown'
LOG: 'key', 'mouseMove'
LOG: 'key', 'mouseOut'
LOG: 'key', 'mouseOver'
LOG: 'key', 'mouseUp'
LOG: 'key', 'paste'
LOG: 'key', 'reset'
LOG: 'key', 'scroll'
LOG: 'key', 'submit'
LOG: 'key', 'touchCancel'
LOG: 'key', 'touchEnd'
LOG: 'key', 'touchMove'
LOG: 'key', 'touchStart'
LOG: 'key', 'wheel'
LOG: 'key', 'mouseEnter'
LOG: 'key', 'mouseLeave'
LOG: 'key', 'change'
LOG: 'key', 'compositionEnd'
LOG: 'key', 'compositionStart'
LOG: 'key', 'compositionUpdate'
LOG: 'key', 'select'