Bug 246575 Drawing surface leak fix. r=thesuckiestemail@yahoo.se. No sr required - BeOS port-only change

gfx/src/beos/nsRenderingContextBeOS.cpp

@@ -106,6 +106,7 @@ NS_IMETHODIMP nsRenderingContextBeOS::Init(nsIDeviceContext *aContext, nsDrawing
 	mContext = aContext;
 	NS_IF_ADDREF(mContext);
 	mSurface = (nsDrawingSurfaceBeOS *)aSurface;
+	mOffscreenSurface = mSurface;
 	NS_ADDREF(mSurface);
 	return (CommonInit());
 }