Mark redirect-on-back-updates-history-item.html as flaky timeout

No-Try: true
Tbr: clamy@chromium.org
Bug: 983799
Change-Id: I7d4459c59aea0f0f19008d8f81778fad56ac0390
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1703465Reviewed-by: Makoto Shimazu <shimazu@chromium.org>
Commit-Queue: Makoto Shimazu <shimazu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#677599}

third_party/blink/web_tests/TestExpectations

@@ -2179,6 +2179,10 @@ crbug.com/891427 [ Mac Win7 ] virtual/mouseevent_fractional/fast/events/touch/ge
 # ====== OOPIF-mode failures until here ======
 
 
+### sheriff 2019-07-16
+crbug.com/983799 [ Win ] http/tests/navigation/redirect-on-back-updates-history-item.html [ Timeout Pass ]
+crbug.com/983799 [ Win ] virtual/blink-cors/http/tests/navigation/redirect-on-back-updates-history-item.html [ Timeout Pass ]
+
 ### sheriff 2018-05-28
 
 crbug.com/767269 [ Win ] inspector-protocol/layout-fonts/cjk-ideograph-fallback-by-lang.js [ Pass Failure ]