removed e.stopPropagation() from onKeyDown (#2354)
* removed e.stopPropagation() from onKeyDown
* added check if propgation has already been stopped
* added test for isPropagationStopped
* removed stopPropagation completely, also removed the test
Co-authored-by: Daniel Lu <dlu@livefyre.com>
Co-authored-by: Robert Snow <rsnow@adobe.com>
