#416: M1365189 M1365875

layout/svg/nsSVGIntegrationUtils.cpp

@@ -788,6 +788,15 @@ nsSVGIntegrationUtils::DrawableFromPaintServer(nsIFrame*         aFrame,
     return drawable.forget();
   }
 
+#if DEBUG
+  if (aFrame->IsFrameOfType(nsIFrame::eSVG) &&
+      !static_cast<nsISVGChildFrame*>(do_QueryFrame(aFrame))) {
+    MOZ_ASSERT_UNREACHABLE("We should prevent painting of unpaintable SVG "
+                           "before we get here");
+    return nullptr;
+  }
+#endif
+
   // We don't want to paint into a surface as long as we don't need to, so we
   // set up a drawing callback.
   RefPtr<gfxDrawingCallback> cb =