[FedCM] Fix the implementation of test_driver.get_fedcm_dialog_title

It is supposed to return a dictionary:
https://fedidcg.github.io/FedCM/#webdriver-gettitle

This was causing the test to fail when run against "real"
webdriver:
https://wpt.fyi/results/credential-management/fedcm-context.https.html?label=experimental&label=master

R=npm@chromium.org

Bug: 331237776
Change-Id: I25168e475cd15b93e3fb4f175ec697ab5b027023
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5394270
Reviewed-by: Nicolás Peña <npm@chromium.org>
Commit-Queue: Christian Biesinger <cbiesinger@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1277980}
diff --git a/credential-management/fedcm-context.https.html b/credential-management/fedcm-context.https.html
index bc1f96e..7b3e103 100644
--- a/credential-management/fedcm-context.https.html
+++ b/credential-management/fedcm-context.https.html
@@ -16,32 +16,32 @@
 
 fedcm_test(async t => {
   let p = navigator.credentials.get(request_options_with_mediation_required());
-  const title = await fedcm_get_title_promise(t);
-  assert_true(title.toLowerCase().includes('sign in'));
+  const result = await fedcm_get_title_promise(t);
+  assert_true(result.title.toLowerCase().includes('sign in'));
   window.test_driver.select_fedcm_account(0);
   return p;
 }, "FedCM call defaults to 'signin' context.");
 
 fedcm_test(async t => {
   let p = navigator.credentials.get(request_options_with_context("manifest.py", "signup"));
-  const title = await fedcm_get_title_promise(t);
-  assert_true(title.toLowerCase().includes('sign up'));
+  const result = await fedcm_get_title_promise(t);
+  assert_true(result.title.toLowerCase().includes('sign up'));
   window.test_driver.select_fedcm_account(0);
   return p;
 }, "FedCM with 'signup' context.");
 
 fedcm_test(async t => {
   let p = navigator.credentials.get(request_options_with_context("manifest.py", "use"));
-  const title = await fedcm_get_title_promise(t);
-  assert_true(title.toLowerCase().includes('use'));
+  const result = await fedcm_get_title_promise(t);
+  assert_true(result.title.toLowerCase().includes('use'));
   window.test_driver.select_fedcm_account(0);
   return p;
 }, "FedCM with 'use' context.");
 
 fedcm_test(async t => {
   let p = navigator.credentials.get(request_options_with_context("manifest.py", "continue"));
-  const title = await fedcm_get_title_promise(t);
-  assert_true(title.toLowerCase().includes('continue'));
+  const result = await fedcm_get_title_promise(t);
+  assert_true(result.title.toLowerCase().includes('continue'));
   window.test_driver.select_fedcm_account(0);
   return p;
 }, "FedCM with 'continue' context.");