Allow Create-protocols-repeated-case-insensitive.any.js to fail on Win7

See https://crbug.com/836763

TBR=qyearsley@chromium.org

No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 836763
Change-Id: I91e1edb6e7fac3aa3957b2ac0c20fc25d628be7d
Reviewed-on: https://chromium-review.googlesource.com/1027850
Commit-Queue: Henrik Boström <hbos@chromium.org>
Reviewed-by: Henrik Boström <hbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553512}

third_party/WebKit/LayoutTests/TestExpectations

@@ -4138,3 +4138,6 @@ crbug.com/836241 [ Linux ] virtual/android/fullscreen/video-controls-timeline.ht
 crbug.com/836242 [ Linux Mac Win ] fast/loader/reload-zero-byte-plugin.html [ Pass Failure ]
 crbug.com/836275 [ Linux Mac ] fast/spatial-navigation/snav-two-elements-one-line.html [ Pass Failure ]
 crbug.com/836295 [ Win ] svg/animations/reinserting-svg-into-document.html [ Pass Failure ]
+
+# Sheriff 2018-04-25
+crbug.com/836763 [ Win7 ] external/wpt/websockets/Create-protocols-repeated-case-insensitive.any.js [ Pass Failure ]