Mark RTCPeerConnection-iceConnectionState.https.html flaky

Tbr: tommi@chromium.org
No-try: true
Bug: 1157849
Change-Id: Ideaf0c3f6ee4dfe5bbd99857f93071e0376cb032
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2585690
Commit-Queue: Ella Ge <eirage@chromium.org>
Reviewed-by: Ella Ge <eirage@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836125}

third_party/blink/web_tests/TestExpectations

@@ -5870,3 +5870,7 @@ crbug.com/1154178 external/wpt/webmessaging/broadcastchannel/basics.html [ Pass
 
 # DevTools roll
 crbug.com/1024752 http/tests/devtools/sources/inline-styles-scripts-locations.js [ Skip ]
+
+# Sheriff 2020-12-11
+# Flaking on Linux Trusty
+crbug.com/1157849 [ Linux Release ] external/wpt/webrtc/RTCPeerConnection-iceConnectionState.https.html [ Pass Timeout ]