animator: fix removal of multiple keys
animator: fix removal of multiple keys

When removing keys, sometimes a couple of keys would be remaining.

Distrotech/clutter,dlespiau/clutter,djdeath/clutter,djdeath/clutter-multithreaded,nobled/clutter,nobled/clutter,spatulasnout/clutter,djdeath/clutter-android,collects/clutter,GNOME/clutter,Distrotech/clutter,djdeath/clutter-multithreaded,heysion/clutter-clone,heysion/clutter-clone,dlespiau/clutter,djdeath/clutter-multithreaded,collects/clutter,collects/clutter,spatulasnout/clutter,kerrickstaley/clutter-vala,ebassi/clutter,djdeath/clutter,ebassi/clutter,jigpu/clutter,Distrotech/clutter,heysion/clutter-clone,GNOME/clutter,jigpu/clutter,collects/clutter,rkudiyarov/clutter_osx,jigpu/clutter,GNOME/clutter,heysion/clutter-clone,kerrickstaley/clutter-vala,rkudiyarov/clutter_osx,djdeath/clutter-android,dlespiau/clutter,ebassi/clutter,spatulasnout/clutter,rkudiyarov/clutter_osx,GNOME/clutter,spatulasnout/clutter,kerrickstaley/clutter-vala,collects/clutter,nobled/clutter,djdeath/clutter,GNOME/clutter,djdeath/clutter-android,kerrickstaley/clutter-vala,jigpu/clutter,djdeath/clutter-multithreaded,Distrotech/clutter,heysion/clutter-clone,djdeath/clutter-android,ebassi/clutter,djdeath/clutter,Distrotech/clutter,djdeath/clutter-android,Distrotech/clutter,djdeath/clutter,ebassi/clutter,rkudiyarov/clutter_osx,djdeath/clutter,jigpu/clutter,jigpu/clutter,spatulasnout/clutter