fix(cdn): Polyfill Object.assign for ES5

I copy-pasted the polyfill that rollup-typescript uses for object spreads.

Author: mydea

dev-packages/rollup-utils/polyfills/es5.js

@@ -39,3 +39,13 @@ if (!('endsWith' in String.prototype)) {
     return i > -1 && i === this.length - searchElement.length;
   };
 }
+
+if (!('assign' in Object)) {
+  Object.assign = function __assign(t) {
+    for (var s, i = 1, n = arguments.length; i < n; i++) {
+      s = arguments[i];
+      for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p)) t[p] = s[p];
+    }
+    return t;
+  };
+}