Scroll To Top Android de lameo

Adds a very simple scroll to top button for all URLs.

- Button appears at the bottom/middle of the screen during scrolling if the element is scrolled below a threshold.
- Button will hide itself after 1 second if no more scrolling occurs or the page is scrolled above the threshold again.
- The scrolling will apply to whichever element was last scrolled.

Sample screen captures of the functionality of the extension is given on my Github page:
https://github.com/lamelameo/ScrollToTop-Firefox-for-Android-Extension