Use asserts in origin trials layout tests

third_party/WebKit/LayoutTests/http/tests/origin_trials/webexposed/foreignfetch-origin-trial-interfaces.html

Index: third_party/WebKit/LayoutTests/http/tests/origin_trials/webexposed/foreignfetch-origin-trial-interfaces.html
diff --git a/third_party/WebKit/LayoutTests/http/tests/origin_trials/webexposed/foreignfetch-origin-trial-interfaces.html b/third_party/WebKit/LayoutTests/http/tests/origin_trials/webexposed/foreignfetch-origin-trial-interfaces.html
index 99d160f75607e96bc63d38b63ff240d2bde7cc2c..5db6896e08579797262d122ef8b56d4bf465b307 100644
--- a/third_party/WebKit/LayoutTests/http/tests/origin_trials/webexposed/foreignfetch-origin-trial-interfaces.html
+++ b/third_party/WebKit/LayoutTests/http/tests/origin_trials/webexposed/foreignfetch-origin-trial-interfaces.html
@@ -10,28 +10,11 @@ generate_token.py  http://127.0.0.1:8000 ForeignFetch --expire-timestamp=2000000
 <script src="../../resources/origin-trials-helper.js"></script>
 <script src="../../serviceworker/resources/test-helpers.js"></script>
 <script>
-promise_test(t => {
-    var script =
-        './resources/foreignfetch-origin-trial-interfaces-worker.php';
-    var scope =
-        './resources/foreignfetch-origin-trial-interfaces-scope-disabled';
-    return OriginTrialsHelper.check_interfaces_in_sw(t, script, scope)
-      .then(message => {
-        console.log('Interfaces in Service Worker - no origin trial\n' + message);
-      });
-  }, "ForeignFetch related interfaces in SW - no origin trial.");
-
-promise_test(t => {
-    var script =
-        './resources/foreignfetch-origin-trial-interfaces-worker.php?' +
-        'origintrial=true';
-    var scope =
-        './resources/foreignfetch-origin-trial-interfaces-scope-enabled';
-    return OriginTrialsHelper.check_interfaces_in_sw(t, script, scope)
-      .then(message => {
-        console.log('Interfaces in Service Worker - origin trial enabled.\n' +
-                    message);
-      });
-  }, "ForeignFetch related interfaces in SW - origin trial enabled.");
+service_worker_test(
+  'resources/foreignfetch-origin-trial-interfaces-worker-disabled.js',
+  'ForeignFetch related interfaces in SW - no origin trial.');
 
+service_worker_test(
+  'resources/foreignfetch-origin-trial-interfaces-worker-enabled.php',
+  'ForeignFetch related interfaces in SW - origin trial enabled.');
 </script>