Implement step 6 of media element 'time marches on' algoritm

tests/wpt/metadata/html/semantics/embedded-content/media-elements/autoplay-with-broken-track.html.ini

@@ -1,7 +1,9 @@
 [autoplay-with-broken-track.html]
   expected: TIMEOUT
   [<video autoplay> with <track> child]
-    expected: TIMEOUT
+    expected:
+      if debug and (os == "mac") and (version == "OS X 10.14.1") and (processor == "x86_64") and (bits == 64): PASS
+      TIMEOUT
 
   [<video autoplay> with <track src=\"invalid://url\" default=\"\"> child]
     expected: TIMEOUT

tests/wpt/metadata/html/semantics/embedded-content/media-elements/event_timeupdate.html.ini

@@ -2,9 +2,6 @@
   type: testharness
   disabled: Until https://github.com/servo/servo/pull/22477 is merged
   expected: TIMEOUT
-  [setting src attribute on a sufficiently long autoplay audio should trigger timeupdate event]
-    expected: NOTRUN
-
   [setting src attribute on a sufficiently long autoplay video should trigger timeupdate event]
     expected: NOTRUN
 

tests/wpt/metadata/html/semantics/embedded-content/media-elements/event_timeupdate_noautoplay.html.ini

@@ -5,6 +5,4 @@
   [calling play() on a sufficiently long audio should trigger timeupdate event]
     expected: NOTRUN
 
-  [calling play() on a sufficiently long video should trigger timeupdate event]
-    expected: FAIL