Mark external/wpt/.../popup-coop-by-sw.https.html as Pass, Timeout

This cl adds Timeout to external/wpt/html/cross-origin-opener-policy/popup-coop-by-sw.https.html's
expectations since it is flaky on multiple platforms:
https://analysis.chromium.org/p/chromium/flake-portal/flakes/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVybAsSBUZsYWtlImFjaHJvbWl1bUBibGlua193ZWJfdGVzdHNAZXh0ZXJuYWwvd3B0L2h0bWwvY3Jvc3Mtb3JpZ2luLW9wZW5lci1wb2xpY3kvcG9wdXAtY29vcC1ieS1zdy5odHRwcy5odG1sDA

TBR: pmeuleman@chromium.org
Change-Id: I2caf3aeeeb020a8d1b6c7d4fe4b2cbd227280bf1
Bug: 1071909
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2153022Reviewed-by: Sahel Sharify <sahel@chromium.org>
Commit-Queue: Sahel Sharify <sahel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760179}

third_party/blink/web_tests/TestExpectations

@@ -6689,5 +6689,8 @@ crbug.com/1069714 [ Mac10.13 ] external/wpt/webrtc/RTCRtpSender-replaceTrack.htt
 # Sheriff 2020-04-10
 crbug.com/1068681 fast/peerconnection/RTCPeerConnection-insertable-streams.html [ Pass Failure Timeout ]
 
+# Sheriff 2020-04-17
+crbug.com/1071909 external/wpt/html/cross-origin-opener-policy/popup-coop-by-sw.https.html [ Pass Timeout ]
+
 # QUIC reordered versions to prefer IETF QUIC
 crbug.com/1070747 external/wpt/webrtc-quic/* [ Skip ]