Form controls focused by mouse press should not show focus rings when the page looses focus and gets focus again.

dispatchFocusEvent(0, FocusDirectionNone) was dispatched in this case, but we
want to keep the last state of m_wasFocusedByMouse. We introduce
FocusDirectionPage to distinguish this case from others.

We can't test this behavior in Blink because page focus is not testable.

BUG=268800,271289

Review URL: https://chromiumcodereview.appspot.com/23164002

git-svn-id: svn://svn.chromium.org/blink/trunk@156133 bbb929c8-8fbe-4397-9dbb-9b2b20218538