Mark http-state/domain-tests.html as slow since it's been timing out.

TBR=pkasting@chromium.org
NOTRY=true (disabling tests)

Bug: 875195
Change-Id: I774947560cb501d60e24fc64b617ab6cc6653716
Reviewed-on: https://chromium-review.googlesource.com/1180486Reviewed-by: apacible <apacible@chromium.org>
Commit-Queue: apacible <apacible@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584237}

third_party/WebKit/LayoutTests/SlowTests

@@ -560,6 +560,7 @@ crbug.com/874695 external/wpt/content-security-policy/securitypolicyviolation/in
 crbug.com/874695 external/wpt/content-security-policy/securitypolicyviolation/targeting.html [ Slow ]
 crbug.com/874695 external/wpt/content-security-policy/style-src/style-src-multiple-policies-multiple-hashing-algorithms.html [ Slow ]
 crbug.com/874695 external/wpt/cookies/samesite/form-post-blank.html [ Slow ]
+crbug.com/875195 external/wpt/cookies/http-state/domain-tests.html [ Slow ]
 crbug.com/874695 external/wpt/cors/304.htm [ Slow ]
 crbug.com/874695 external/wpt/cors/origin.htm [ Slow ]
 crbug.com/874695 external/wpt/cors/preflight-cache.htm [ Slow ]