--- a/testing/web-platform/meta/MANIFEST.json
+++ b/testing/web-platform/meta/MANIFEST.json
@@ -604183,17 +604183,17 @@
    "c939271e717288203a5a298b95a7328100bd7c80",
    "support"
   ],
   "service-workers/service-worker/resources/resource-timing-iframe.sub.html": [
    "75bd224a9680af0557c53fb6e77645e4e0b8173d",
    "support"
   ],
   "service-workers/service-worker/resources/resource-timing-worker.js": [
-   "2a47775874086c1cdff257e3243af1af0b5e84be",
+   "04a965dc0324c035bb3331e546d9bb43230d5eac",
    "support"
   ],
   "service-workers/service-worker/resources/respond-then-throw-worker.js": [
    "d57215bcad8a3966175930642dfd34281b11aeff",
    "support"
   ],
   "service-workers/service-worker/resources/respond-with-body-accessed-response-iframe.html": [
    "d3d543503ab9c4398a674105a7c67f1a2e74cde7",

--- a/testing/web-platform/tests/service-workers/service-worker/resources/resource-timing-worker.js
+++ b/testing/web-platform/tests/service-workers/service-worker/resources/resource-timing-worker.js
@@ -1,5 +1,9 @@
 self.addEventListener('fetch', function(event) {
-    if (event.request.url.indexOf('dummy.js') != -1) {
-      event.respondWith(fetch('empty.js'));
-    }
-  });
+  if (event.request.url.indexOf('dummy.js') != -1) {
+    event.respondWith(new Promise(resolve => {
+      // Slightly delay the response so we ensure we get a non-zero
+      // duration.
+      setTimeout(_ => resolve(new Response('// Empty javascript')), 50);
+    }));
+  }
+});