Harden named arguments if a hard split occurs in the positional ones.

test/splitting/function_arguments.stmt

Index: test/splitting/function_arguments.stmt
diff --git a/test/splitting/function_arguments.stmt b/test/splitting/function_arguments.stmt
index cc8d8c6f0de5ed25313c47de50f6e1b7427593e1..450b53a183411c37f1b1bbd8c4d0984b33aeb073 100644
--- a/test/splitting/function_arguments.stmt
+++ b/test/splitting/function_arguments.stmt
@@ -167,4 +167,15 @@ obj.outer(
     argument,
     obj.inner(() {
       body;
-    }));
+    }));
+>>> force named args to split on positional function
+function(argument, () {;},
+    named: argument, another: argument);
+<<<
+function(
+    argument,
+    () {
+      ;
+    },
+    named: argument,
+    another: argument);