Add a date/details link to FileError deprecation warning

Intent: https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/kJMa2rpAYqI
Dashboard: https://www.chromestatus.com/feature/6687420359639040

R=foolip@chromium.org
BUG=496901

Review-Url: https://codereview.chromium.org/2023123002
Cr-Commit-Position: refs/heads/master@{#405230}
1 file changed