stage: implicitly clip to stage window bounds
stage: implicitly clip to stage window bounds

This implicitly intersects any clip for redrawing with the stage window
bounds. Without this we were sometimes trying to set huge off screen
scissors leading to undefined clipping results.

Reviewed-by: Emmanuele Bassi <049ee2061f71220e5aaf33f5be422fc2a2b06a44@linux.intel.com>

kerrickstaley/clutter-vala,djdeath/clutter,collects/clutter,djdeath/clutter,djdeath/clutter-multithreaded,GNOME/clutter,heysion/clutter-clone,djdeath/clutter,GNOME/clutter,djdeath/clutter-android,jigpu/clutter,GNOME/clutter,GNOME/clutter,kerrickstaley/clutter-vala,Distrotech/clutter,heysion/clutter-clone,ebassi/clutter,kerrickstaley/clutter-vala,djdeath/clutter,collects/clutter,jigpu/clutter,djdeath/clutter-multithreaded,Distrotech/clutter,Distrotech/clutter,heysion/clutter-clone,Distrotech/clutter,jigpu/clutter,kerrickstaley/clutter-vala,djdeath/clutter,Distrotech/clutter,heysion/clutter-clone,jigpu/clutter,ebassi/clutter,djdeath/clutter-android,djdeath/clutter-multithreaded,djdeath/clutter-android,djdeath/clutter-android,collects/clutter,ebassi/clutter,heysion/clutter-clone,jigpu/clutter,ebassi/clutter,djdeath/clutter-multithreaded,djdeath/clutter,GNOME/clutter,djdeath/clutter-android,jigpu/clutter,ebassi/clutter,collects/clutter,collects/clutter,Distrotech/clutter