Check that getComputedStyle causes a style recalc when necessary, and only when necessary.
On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
PASS internals.updateStyleAndReturnAffectedElementCount() is 0
PASS internals.updateStyleAndReturnAffectedElementCount() is 1
PASS internals.updateStyleAndReturnAffectedElementCount() is 1
PASS successfullyParsed is true
TEST COMPLETE