[dart2js] (New RTI) Check function subtypes after checking for FutureOr.

Change-Id: I0cde41a8010563d7288d5473669cb87f0064ce63
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/112483
Reviewed-by: Stephen Adams <sra@google.com>
Commit-Queue: Mayank Patke <fishythefish@google.com>

sdk/lib/_internal/js_runtime/lib/rti.dart

@@ -1877,14 +1877,6 @@ bool _isSubtype(universe, Rti s, sEnv, Rti t, tEnv) {
 
   if (isNullType(s)) return true;
 
-  if (Rti._isFunctionType(t)) {
-    return _isFunctionSubtype(universe, s, sEnv, t, tEnv);
-  }
-
-  if (Rti._isFunctionType(s)) {
-    return isFunctionType(t);
-  }
-
   if (isFutureOrType(t)) {
     // [t] is FutureOr<T>.
     Rti tTypeArgument = Rti._getFutureOrArgument(t);
@@ -1904,6 +1896,14 @@ bool _isSubtype(universe, Rti s, sEnv, Rti t, tEnv) {
     }
   }
 
+  if (Rti._isFunctionType(t)) {
+    return _isFunctionSubtype(universe, s, sEnv, t, tEnv);
+  }
+
+  if (Rti._isFunctionType(s)) {
+    return isFunctionType(t);
+  }
+
   assert(Rti._getKind(t) == Rti.kindInterface);
   String tName = Rti._getInterfaceName(t);
   var tArgs = Rti._getInterfaceTypeArguments(t);