Merge lp://qastaging/~gue5t/midori/exec-windowclose into lp://qastaging/midori

Fix warnings when starting with --execute WindowClose

Right now, starting Midori with "--execute WindowClose" causes a number of assertion failures (more if run with -p):

$ midori -p -e WindowClose

(midori4:21698): Gdk-CRITICAL **: IA__gdk_event_free: assertion 'event != NULL' failed

** (midori4:21698): CRITICAL **: midori_browser_activate_action: assertion 'MIDORI_IS_BROWSER (browser)' failed

** (midori4:21698): CRITICAL **: midori_browser_activate_action: assertion 'MIDORI_IS_BROWSER (browser)' failed

** (midori4:21698): CRITICAL **: midori_browser_activate_action: assertion 'MIDORI_IS_BROWSER (browser)' failed

(midori4:21698): GLib-GObject-WARNING **: instance with invalid (NULL) class pointer

(midori4:21698): GLib-GObject-CRITICAL **: g_signal_connect_data: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed

(midori4:21698): GLib-GObject-WARNING **: instance with invalid (NULL) class pointer

(midori4:21698): GLib-GObject-CRITICAL **: g_signal_connect_data: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed
^C

This fixes the assertion failures, but it does not fix the fact that the Midori process does not exit when started with "--execute WindowClose" *and* -p. After this patch the execute command works perfectly without -p and quietly sits there with -p.

The problem was twofold: we were inadvertently passing a NULL GdkEvent when emitting the delete_event signal, and in private mode we were running commands before enabling "built-in" extensions. This constructs a GdkEvent to fix the former and reorders things to a more sane sequence of events to fix the latter.