Bug 1518754 [wpt PR 14757] - Update wpt metadata, a=testonly

wpt-pr: 14757
wpt-type: metadata

testing/web-platform/meta/webrtc/RTCRtpReceiver-getSynchronizationSources.https.html.ini

@@ -1,4 +1,26 @@
 [RTCRtpReceiver-getSynchronizationSources.https.html]
+  expected: TIMEOUT
   [getContributingSources() should return list of CSRC after connection is established]
     expected: FAIL
 
+  [[video\] RTCRtpSynchronizationSource.timestamp is a number]
+    expected: NOTRUN
+
+  [[audio-only\] RTCRtpSynchronizationSource.voiceActivityFlag is a boolean]
+    expected: NOTRUN
+
+  [[video\] getSynchronizationSources() does not contain SSRCs older than 10 seconds]
+    expected: NOTRUN
+
+  [[video\] getSynchronizationSources() eventually returns a non-empty list]
+    expected: TIMEOUT
+
+  [[video\] RTCRtpSynchronizationSource.timestamp is comparable to performance.timeOrigin + performance.now()]
+    expected: NOTRUN
+
+  [[audio-only\] RTCRtpSynchronizationSource.audioLevel is a number [0, 1\]]
+    expected: NOTRUN
+
+  [[video\] RTCRtpSynchronizationSource.source is a number]
+    expected: NOTRUN
+