Fixed Mac OS Canvas / CALayer.

http://hg.openjdk.java.net/jdk8/awt/jdk/rev/65d874d16d59
JAWT native CALayer not positioned over Canvas
(Reviewed-by: art, anthony)
Initialy, the layer bounds have the Y coord originating not as
expected. java7 only seems to provoke that issue. so cpeer would update
bounds as necessary now.
by broumbroum