Disable another test.

TBR=grunell@chromium.org

Bug: chromium:943975
Change-Id: I19c03824b57cc0617c759acf2e3129c361861722
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1613185Reviewed-by: Harald Alvestrand <hta@chromium.org>
Reviewed-by: Henrik Grunell <grunell@chromium.org>
Commit-Queue: Harald Alvestrand <hta@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659985}

third_party/blink/web_tests/TestExpectations

@@ -5582,3 +5582,4 @@ crbug.com/937991 [ Win7 Release ] http/tests/devtools/cache-storage/cache-data.j
 # https://webrtc-review.googlesource.com/c/src/+/135948
 crbug.com/943975 external/wpt/webrtc/RTCDataChannel-send.html [ Pass Failure ]
 crbug.com/943975 external/wpt/webrtc/RTCSctpTransport-maxMessageSize.html [ Pass Failure ]
+crbug.com/943975 virtual/webrtc-wpt-plan-b/external/wpt/webrtc/RTCSctpTransport-maxMessageSize.html [ Pass Failure ]