Import //fetch from Web Platform Tests.

third_party/WebKit/LayoutTests/external/wpt/fetch/api/redirect/redirect-count.js

+if (this.document === undefined) {
+  importScripts("/resources/testharness.js");
+  importScripts("../resources/utils.js");
+  importScripts("/common/utils.js");
+}
+
+function redirectCount(desc, redirectUrl, redirectLocation, redirectStatus, maxCount, shouldPass) {
+  var uuid_token = token();
+
+  var urlParameters = "?token=" + uuid_token + "&max_age=0";
+  urlParameters += "&redirect_status=" + redirectStatus;
+  urlParameters += "&max_count=" + maxCount;
+  if (redirectLocation)
+    urlParameters += "&location=" + encodeURIComponent(redirectLocation);
+
+  var url = redirectUrl;
+  var requestInit = {"redirect": "follow"};
+
+  promise_test(function(test) {
+    return fetch(RESOURCES_DIR + "clean-stash.py?token=" + uuid_token).then(function(resp) {
+      assert_equals(resp.status, 200, "Clean stash response's status is 200");
+
+      if (!shouldPass)
+        return promise_rejects(test, new TypeError(), fetch(url + urlParameters, requestInit));
+
+      return fetch(url + urlParameters, requestInit).then(function(resp) {
+        assert_equals(resp.status, 200, "Response's status is 200");
+        return resp.text();
+      }).then(function(body) {
+        assert_equals(body, maxCount.toString(), "Redirected " + maxCount + " times");
+      });
+    });
+  }, desc);
+}
+
+var redirUrl = RESOURCES_DIR + "redirect.py";
+
+for (var statusCode of [301, 302, 303, 307, 308]) {
+  redirectCount("Redirect " + statusCode + " 20 times", redirUrl, redirUrl, statusCode, 20, true);
+  redirectCount("Redirect " + statusCode + " 21 times", redirUrl, redirUrl, statusCode, 21, false);
+}
+
+done();