Fix webcomponents polyfill loading

ext/src/shim/contentBridge.ts

@@ -1,6 +1,19 @@
 "use strict";
 
 import { onMessageResponse, sendMessage } from "./eventMessageChannel";
+import { loadScript } from "../lib/utils";
+
+
+const { isFramework }
+    : { isFramework: boolean } = (window as any);
+
+/**
+ * Framework API library requires webcomponents for the cast
+ * button custom element (<google-cast-launcher>).
+ */
+if (isFramework) {
+    loadScript(browser.runtime.getURL("vendor/webcomponents-lite.js"));
+}
 
 
 // Message port to background script