web: Try playAndMonitor for embed_unexpected_string

Author: danielhjacobs

web/packages/selfhosted/test/polyfill/embed_unexpected_string/test.ts

@@ -12,7 +12,10 @@ describe("Embed with unexpected string", () => {
 
     it("polyfills with ruffle", async () => {
         await injectRuffleAndWait(browser);
-        await browser.$("<ruffle-embed />").waitForExist();
+        await playAndMonitor(
+            browser,
+            await browser.$("#test-container").$("<ruffle-embed />"),
+        );
         const actual = await browser
             .$("#test-container")
             .getHTML({ includeSelectorTag: false, pierceShadowRoot: false });