Bug 1602989 - Remove warning when serialising nsIVariant. r=mattwoodrow

The type doesn't need to be sent across IPC anyway.

Differential Revision: https://phabricator.services.mozilla.com/D60212

--HG--
extra : moz-landing-system : lando

dom/ipc/PropertyBagUtils.cpp

@@ -109,7 +109,7 @@ void IPDLParamTraits<nsIVariant*>::Write(Message* aMsg, IProtocol* aActor,
       free(iid);
       nsCOMPtr<nsIURI> uri = do_QueryInterface(value);
       if (value && !uri) {
-        NS_WARNING("we only accept nsIURI interface type, patch welcome");
+        // We only accept nsIURI interface type, patch welcome.
         variant.type() = nsIDataType::VTYPE_EMPTY;
       }
       variant.data() = uri;