Draggable: Check for grid elements set to 0 to prevent divide by 0 error causing invalid argument errors in IE. Fixed #6950 - ie 8 invalid drag and drop error

(cherry picked from commit d136e43)

Author: kborchers

ui/jquery.ui.draggable.js

@@ -436,10 +436,11 @@ $.widget("ui.draggable", $.ui.mouse, {
 			}
 
 			if(o.grid) {
-				var top = this.originalPageY + Math.round((pageY - this.originalPageY) / o.grid[1]) * o.grid[1];
+				//Check for grid elements set to 0 to prevent divide by 0 error causing invalid argument errors in IE (see ticket #6950)
+				var top = o.grid[1] ? this.originalPageY + Math.round((pageY - this.originalPageY) / o.grid[1]) * o.grid[1] : this.originalPageY;
 				pageY = containment ? (!(top - this.offset.click.top < containment[1] || top - this.offset.click.top > containment[3]) ? top : (!(top - this.offset.click.top < containment[1]) ? top - o.grid[1] : top + o.grid[1])) : top;
 
-				var left = this.originalPageX + Math.round((pageX - this.originalPageX) / o.grid[0]) * o.grid[0];
+				var left = o.grid[0] ? this.originalPageX + Math.round((pageX - this.originalPageX) / o.grid[0]) * o.grid[0] : this.originalPageX;
 				pageX = containment ? (!(left - this.offset.click.left < containment[0] || left - this.offset.click.left > containment[2]) ? left : (!(left - this.offset.click.left < containment[0]) ? left - o.grid[0] : left + o.grid[0])) : left;
 			}