fix(ngAnimate): ensure that minified repaint code isn't removed

Closes angular#9936

Author: matsko

src/ngAnimate/animate.js

@@ -432,8 +432,11 @@ angular.module('ngAnimate', ['ng'])
         //so that all the animated elements within the animation frame
         //will be properly updated and drawn on screen. This is
         //required to perform multi-class CSS based animations with
-        //Firefox. DO NOT REMOVE THIS LINE.
-        var a = bod.offsetWidth + 1;
+        //Firefox. DO NOT REMOVE THIS LINE. DO NOT OPTIMIZE THIS LINE.
+        //THE MINIFIER WILL REMOVE IT OTHERWISE WHICH WILL RESULT IN AN
+        //UNPREDICTABLE BUG THAT IS VERY HARD TO TRACK DOWN AND WILL
+        //TAKE YEARS AWAY FROM YOUR LIFE!
+        bod.cachedWidth = bod.offsetWidth;
         fn();
       });
     };