Handle Key_Up/Key_Down while debugging.

def _event_filter_console_keypress(self, event):
        """Handle Key_Up/Key_Down while debugging."""
        key = event.key()
        if self._reading:
            self._control.current_prompt_pos = self._prompt_pos
            if key == Qt.Key_Up:
                self._control.browse_history(backward=True)
                return True
            elif key == Qt.Key_Down:
                self._control.browse_history(backward=False)
                return True
            elif key in (Qt.Key_Return, Qt.Key_Enter):
                self._control.reset_search_pos()
            else:
                self._control.hist_wholeline = False
            return super(DebuggingWidget,
                         self)._event_filter_console_keypress(event)
        else:
            return super(DebuggingWidget,
                         self)._event_filter_console_keypress(event)