Fix leak when calling methods with unowned delegate parameters
Fix leak when calling methods with unowned delegate parameters

Fixes bug 595879.

flobrosch/vala-fixes,jessevdk/vala,spidermonkdust/vala,Distrotech/vala,GNOME/vala,flobrosch/vala-fixes,Distrotech/vala,tjol/vala-tjol,Jc2k/vala,frida/vala,themiwi/vala,frida/vala,spidermonkdust/vala,lovebug356/vala,themiwi/vala,severinh/vala,tjol/vala-tjol,flobrosch/vala-fixes,playya/vala,rvu95/vala,phako/vala,phako/vala,severinh/vala,Jc2k/vala,rvu95/vala,jessevdk/vala,lovebug356/vala,GNOME/vala,rvu95/vala,kamanashisroy/aroop,spidermonkdust/vala,kamanashisroy/aroop,GNOME/vala,severinh/vala,frida/vala,kamanashisroy/aroop,themiwi/vala,frida/vala,tjol/vala-tjol,xdave/pvala,Distrotech/vala,jessevdk/vala,playya/vala,frida/vala,playya/vala,GNOME/vala