Use make_intrusive/make_shared for smart pointer construction.

src/script/image.cpp

@@ -80,7 +80,7 @@ template <> void Reader::handle(ScriptableImage& s) {
     s.script.parse(*this, true);
   } else {
     // a filename
-    s.value = intrusive(new PackagedImage(s.script.unparsed));
+    s.value = make_intrusive<PackagedImage>(s.script.unparsed);
   }
 }
 template <> void Writer::handle(const ScriptableImage& s) {