1 Change class affecting ::backdrop style
3 On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
6 PASS getComputedStyle(dialog, '::backdrop').backgroundColor is not green
7 PASS internals.updateStyleAndReturnAffectedElementCount() is 2
8 PASS getComputedStyle(dialog, '::backdrop').backgroundColor is green
9 PASS successfullyParsed is true