Add stop button "X"

[denuoweb]

See #1047

It has been a few years since your team decided that adding a 'stop loading' button was not worth it. I have recently switched back from DDG to Firefox because of this missing feature after dealing with an unrelated bug.

(A video playback bug that freezes my DDG browser (screen appears solid white until I force quit) on rotating from fullscreen back to normal but this I dont care about as much as being able to stop scripts from loading.)