Add an assertion for the first argument of NewImageChannel, no bug

image/src/imgLoader.cpp

@@ -715,6 +715,8 @@ NewImageChannel(nsIChannel** aResult,
                 nsIPrincipal* aLoadingPrincipal,
                 nsISupports* aRequestingContext)
 {
+  MOZ_ASSERT(aResult);
+
   nsresult rv;
   nsCOMPtr<nsIHttpChannel> newHttpChannel;