Test that 'use' elements are synchronized at run time with the elements they reference.

This test verifies visual synchronization during run time between 'use' instances and the elements they reference. A 'g' element containing two 'rect' elements is referenced via 'use'. One 'rect' is red and the other has no fill specified. DOM synchronization is verified visually by removing the red 'rect'. Presentation attribute synchronization is verified visually by setting the other rect's 'fill' attribute to 'lime'. The 'g' that is referenced is inside of a 'defs' tag so only the 'use' instance is visible.