Obviously, you need to be on Firefox Quantum to see its test results. You can click the A to see test failures (Shift-Click it to open in a new tab).
Edit: I get a 97/100, with the following errors:
Failed 3 of 100 tests.
Test 23 failed: expected '14' but got '5' - wrong exception for createElementNS('null', ':div')
Test 25 failed: wrong exception
Test 26 passed, but took 50ms (less than 30fps)
Test 35 failed: expected '0' but got '1' - root element, with no parent node, claims to be a :first-child
Test 69 passed, but took 2 attempts (less than perfect).
Test 71 passed, but took 214ms (less than 30fps)
Total elapsed time: 1.57s