Convert src/runtime/motion/utils.ts to JavaScript

src/runtime/motion/utils.ts

@@ -1,3 +1,10 @@
-export function is_date(obj: any): obj is Date {
+/** @param {any} obj
+ * @returns {boolean}
+ */
+export function is_date(obj) {
     return Object.prototype.toString.call(obj) === '[object Date]';
 }
+
+
+
+