vala: Skip default-value positioning check for parameters of coroutines
vala: Skip default-value positioning check for parameters of coroutines

https://bugzilla.gnome.org/show_bug.cgi?id=644241

frida/vala,frida/vala,frida/vala,GNOME/vala,GNOME/vala,frida/vala,GNOME/vala,GNOME/vala,frida/vala