Unskip http/tests/security/redirect-BLOCKED-to-localURL.html

This test hasn't failed in the last several runs: http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20Blink&tests=http%2Ftests%2Fsecurity%2Fredirect-BLOCKED-to-localURL.html&showExpectations=true

BUG=231932
TBR=ojan@chromium.org
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/23766012

git-svn-id: svn://svn.chromium.org/blink/trunk@157298 bbb929c8-8fbe-4397-9dbb-9b2b20218538