Tests that the value of the display property on the defs element or on its descendants
doesn't prevent the elements from being referenced.
The test has passed if the following conditions are met:
- there are 8 big rects visible each of a different color.
- on top of the 8 big rects there are 8 circles that contain the reference color, the color of each circle must match the color of the rect to the right of its center
- from the top-left to the top-right corner the colors must be: green, lime, yellow, olive.
- from the bottom-left to the bottom-right corner the colors must be: navy, teal, blue, fuchsia.
