Mark wpt/FileAPI/blob/Blob-stream.any.worker.html as flaky.

It times out now and then.

TBR=mek@chromium.org

Bug: 1092048
Change-Id: I7416f6ee0279c00fa578a51e92e436e67562ac97
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2403483Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805784}

third_party/blink/web_tests/TestExpectations

@@ -6604,6 +6604,7 @@ crbug.com/1112778 external/wpt/html/semantics/scripting-1/the-script-element/mod
 
 # Flaky timeout
 crbug.com/1092048 external/wpt/FileAPI/blob/Blob-stream.any.html [ Pass Timeout ]
+crbug.com/1092048 external/wpt/FileAPI/blob/Blob-stream.any.worker.html [ Pass Timeout ]
 
 # Sheriff 2020-08-04: New wpt tests are failing
 crbug.com/1112771 external/wpt/webhid/idlharness.https.window.html [ Failure ]