Bug 1085810 - [System::Keyboard] Keyboard is not hidden when custom
dialog is shown in system app.
 - Hide the keyboard when the notification is clicked.
Merge pull request #25442 from RudyLu/keyboard/Bug1085810-dismiss_keyboard_notificationClicked

Bug 1085810 - [System::Keyboard] Keyboard is not hidden when custom dialog is.
r=alive