The test has become flaky since: r257901 NOERROR [r257902-r257904] UNKNOWN r257905 TEXT PASS (Expected: PASS) Within the range, r257903 (Fix for test accessibility/mac/aria-liveregions-addedelement.html in IsolatedTree mode) seems a likely cause for the regression.
<rdar://problem/60410346>
*** This bug has been marked as a duplicate of bug 209102 ***