Bug 1535442 - Part 0: Re-enable some test-cases. r=jib

Differential Revision: https://phabricator.services.mozilla.com/D24274

--HG--
extra : moz-landing-system : lando

testing/web-platform/meta/webrtc/RTCPeerConnection-addIceCandidate.html.ini

@@ -1,21 +0,0 @@
-[RTCPeerConnection-addIceCandidate.html]
-  [Add candidate with invalid usernameFragment should reject with OperationError]
-    expected: FAIL
-    bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1535442
-
-  [Add candidate with sdpMid belonging to different usernameFragment should reject with OperationError]
-    expected: FAIL
-    bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1535442
-
-  [addIceCandidate({usernameFragment: usernameFragment1}) should work, and add a=end-of-candidates to the first m-section]
-    expected: FAIL
-    bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1535442
-
-  [addIceCandidate({usernameFragment: usernameFragment2}) should work, and add a=end-of-candidates to the first m-section]
-    expected: FAIL
-    bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1535442
-
-  [addIceCandidate({usernameFragment: "no such ufrag"}) should work, but not add a=end-of-candidates]
-    expected: FAIL
-    bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1535442
-