js-on-sx: js-add ToPrimitive's Date and plain Objects via valueOf/toString

lib/js/runtime.sx

@@ -1969,7 +1969,30 @@
         (get v "__js_number_value__"))
       ((contains? (keys v) "__js_boolean_value__")
         (get v "__js_boolean_value__"))
-      (else v))))
+      ((contains? (keys v) "__js_is_date__")
+        (js-add-call-method v "toString"))
+      (else (js-add-toprim-default v)))))
+
+(define
+  js-add-toprim-default
+  (fn
+    (v)
+    (let
+      ((via-valueof (js-add-call-method v "valueOf")))
+      (cond
+        ((not (= (type-of via-valueof) "dict")) via-valueof)
+        (else (js-add-call-method v "toString"))))))
+
+(define
+  js-add-call-method
+  (fn
+    (v name)
+    (let
+      ((m (js-dict-get-walk v name)))
+      (cond
+        ((js-undefined? m) v)
+        ((not (js-function? m)) v)
+        (else (js-call-with-this v m (list)))))))
 
 (define
   js-add