Cookie Store API: Add back flaky test expectation on Win only.

Flakiness resurfaced on Win7 and Win10 build bots, yielding both
failures and timeouts.

Bug: 827231
Change-Id: I8a56c98a79ee3a5a5ef12c054f344146042cf458
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1699289
Commit-Queue: Victor Costan <pwnall@chromium.org>
Auto-Submit: Staphany Park <staphany@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#677087}

third_party/blink/web_tests/TestExpectations

@@ -5210,8 +5210,7 @@ crbug.com/783301 external/wpt/imagecapture/MediaStreamTrack-getSettings.html [ P
 crbug.com/783301 external/wpt/imagecapture/MediaStreamTrack-getCapabilities.html [ Pass Failure ]
 
 # Cookie Store API
-crbug.com/827231 external/wpt/cookie-store/document_cookie.tentative.html [ Pass Failure ]
-crbug.com/827231 external/wpt/cookie-store/document_cookie.tentative.https.html [ Pass Failure ]
+crbug.com/827231 [ Win ] external/wpt/cookie-store/document_cookie.tentative.https.html [ Pass Failure Timeout ]
 
 # Failing SameSite cookies tests
 crbug.com/843945 external/wpt/cookies/samesite/form-get-blank-reload.html [ Failure ]