WORLD WAR Z-INDEX: Restoration of sanity to revisions/slider/menu z-index values.



The year is 2013. It is a period of DOM unrest. Sliders have hoarded

all available z-index, leading to an arms race. What started as a local

squabble soon escalated into a global conflict. The flyout menus were

the first of the collateral damage, trodden underfoot by mighty warring

enemies they couldn't effectively challenge. It was said they were

betrayed by one of their own: the z-index-power-hungry non-active

currently-hovered submenu, whose z-index-power level was over 9000!



But there is hope. A small band of heroes has emerged. Using their

powers of "what were you thinking?" and "chill, no one needs a z-index

THAT high", they have begun to restore order and harmony to the DOM.



See #24736. Props markjaquith, aaroncampbell, helen.

