[Sheriff] Update TestExpectations

Mark http/tests/devtools/network/oopif-content.js as Flaky on Linux.
It has flaked a lot recently and even caused CQ false rejections.

Bug: 1029528
Change-Id: I682559b28e741b956bf413ebc139da6b8e7556ca
No-Try: True
TBR: caseq@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1946330Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720440}

third_party/blink/web_tests/TestExpectations

@@ -5983,6 +5983,7 @@ crbug.com/1027434 [ Mac ] external/wpt/html/browsers/origin/cross-origin-objects
 
 # Sheriff 2019-12-02
 crbug.com/1029713 external/wpt/cookie-store/cookieStoreManager_getSubscriptions_multiple.tentative.https.any.html [ Pass Failure ]
+crbug.com/1029528 [ Linux ] http/tests/devtools/network/oopif-content.js [ Pass Failure ]
 
 # Temporary suppression to allow Skia change to opaqueness tracking
 crbug.com/1028116 virtual/gpu-rasterization-disable-yuv/images/yuv-decode-eligible/color-profile-border-radius.html [ Pass Failure ]