window: Do not emit notify::skip-taskbar while constructing
Users of notify::skip-taskbar
(in gnome-shell) expects it to only be
emitted when the value has changed. Emitting notify::skip-taskbar
during construction will cause it to be delivered once signal delivery
freeze is thawed, confusing handlers of this signal. In particular, this
results in integer underflow and null pointer dereference in
gnome-shell's app tracker.
How to reproduce:
- Open an application
- Open the right click menu multiple times
- Close the application
- Click on the application icon in GNOME Shell
- Watch the shell process crash