PlzDedicatedWorker: Add clients.claim() tests for nested blob URL worker

This CL adds 3 test cases for clients.claim():
1) a blob URL worker (parent) creates a blob URL worker (child)
2) a blob URL worker (parent) creates a worker (child)
3) a worker (parent) creates a blob URL worker (child)

Bug: 1017034
Change-Id: Iaef9c84661f0fe1c1b10a4a6f8cccc5e839355c8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2638960
Commit-Queue: Asami Doi <asamidoi@chromium.org>
Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845533}

third_party/blink/web_tests/external/wpt/service-workers/service-worker/claim-worker-fetch.https.html

@@ -19,6 +19,18 @@ promise_test((t) => {
   return runTest(t, 'resources/claim-blob-url-worker-fetch-iframe.html');
 }, 'fetch() in blob URL Worker should be intercepted after the client is claimed.');
 
+promise_test((t) => {
+  return runTest(t, 'resources/nested-blob-url-workers.html');
+}, 'fetch() in nested blob URL Worker created from a blob URL Worker should be intercepted after the client is claimed.');
+
+promise_test((t) => {
+  return runTest(t, 'resources/nested-worker-created-from-blob-url-worker.html');
+}, 'fetch() in nested Worker created from a blob URL Worker should be intercepted after the client is claimed.');
+
+promise_test((t) => {
+  return runTest(t, 'resources/nested-blob-url-worker-created-from-worker.html');
+}, 'fetch() in nested blob URL Worker created from a Worker should be intercepted after the client is claimed.');
+
 async function runTest(t, iframe_url) {
   const resource = 'simple.txt';
   const scope = 'resources/';