Position: Restore old flip collision handling

This reverts commit 7f808b2.

Fixes #8710
Ref gh-1071
(cherry picked from commit ebaaca7)

Author: meyertee

ui/position.js

@@ -448,12 +448,12 @@ $.ui.position = {
 				newOverBottom;
 			if ( overTop < 0 ) {
 				newOverBottom = position.top + myOffset + atOffset + offset + data.collisionHeight - outerHeight - withinOffset;
-				if ( ( position.top + myOffset + atOffset + offset) > overTop && ( newOverBottom < 0 || newOverBottom < abs( overTop ) ) ) {
+				if ( newOverBottom < 0 || newOverBottom < abs( overTop ) ) {
 					position.top += myOffset + atOffset + offset;
 				}
 			} else if ( overBottom > 0 ) {
 				newOverTop = position.top - data.collisionPosition.marginTop + myOffset + atOffset + offset - offsetTop;
-				if ( ( position.top + myOffset + atOffset + offset) > overBottom && ( newOverTop > 0 || abs( newOverTop ) < overBottom ) ) {
+				if ( newOverTop > 0 || abs( newOverTop ) < overBottom ) {
 					position.top += myOffset + atOffset + offset;
 				}
 			}