[AshleysBrain]

Previously if you moved an element anywhere else in the DOM for any reason - such as reordering elements, sorting a list, etc. - lots of kinds of elements would be reset: iframes reloaded, transitions/animations are cancelled, video playback is reset, focus is lost, even the scroll position is reset to the top. Some could be worked around (like saving the scroll position and restoring it), but others could not (like iframes being reloaded). Now with moveBefore() all these moves can be done while preserving the element state, which can dramatically simplify the usage of the DOM in some cases.