Revert "Focus changes should be use affectedBy optimization"

Apparently this commit broke two tests:

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20Blink&tests=fast%2Fforms%2Fcalendar-picker%2Fweek-open-picker-with-f4-key.html%C2%A0fast%2Fforms%2Fcalendar-picker%2Fcalendar-picker-f4-key.html

R=eseidel@chromium.org
TBR=

Review URL: https://codereview.chromium.org/61553008

git-svn-id: svn://svn.chromium.org/blink/trunk@161513 bbb929c8-8fbe-4397-9dbb-9b2b20218538