Bug 757346 followup, actually compile

gfx/thebes/gfxPlatformMac.h

@@ -40,7 +40,7 @@ public:
         nsRefPtr<gfxImageSurface> imageSurface = surface->GetAsImageSurface();
         NS_ASSERTION(imageSurface, "Surface cannot be converted to a gfxImageSurface");
 #endif
-        return surface;
+        return surface.forget();
     }
     
     already_AddRefed<gfxASurface> OptimizeImage(gfxImageSurface *aSurface,

gfx/thebes/gfxWindowsPlatform.cpp

@@ -709,7 +709,7 @@ gfxWindowsPlatform::CreateOffscreenSurface(const gfxIntSize& size,
 
     NS_IF_ADDREF(surf);
 
-    return surf;
+    return surf.forget();
 }
 
 already_AddRefed<gfxASurface>