Fetch: redirects to data: URLs

For whatwg/fetch#393.

fetch/redirects/data.window.js

@@ -0,0 +1,27 @@
+async_test(t => {
+  const img = document.createElement("img");
+  img.onload = t.unreached_func();
+  img.onerror = t.step_func_done();
+  img.src = "../api/resources/redirect.py?location=data:image/png%3Bbase64,iVBORw0KGgoAAAANSUhEUgAAAIUAAABqCAIAAAAdqgU8AAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAF6SURBVHhe7dNBDQAADIPA%2Bje92eBxSQUQSLedlQzo0TLQonFWPVoGWjT%2BoUfLQIvGP/RoGWjR%2BIceLQMtGv/Qo2WgReMferQMtGj8Q4%2BWgRaNf%2BjRMtCi8Q89WgZaNP6hR8tAi8Y/9GgZaNH4hx4tAy0a/9CjZaBF4x96tAy0aPxDj5aBFo1/6NEy0KLxDz1aBlo0/qFHy0CLxj/0aBlo0fiHHi0DLRr/0KNloEXjH3q0DLRo/EOPloEWjX/o0TLQovEPPVoGWjT%2BoUfLQIvGP/RoGWjR%2BIceLQMtGv/Qo2WgReMferQMtGj8Q4%2BWgRaNf%2BjRMtCi8Q89WgZaNP6hR8tAi8Y/9GgZaNH4hx4tAy0a/9CjZaBF4x96tAy0aPxDj5aBFo1/6NEy0KLxDz1aBlo0/qFHy0CLxj/0aBlo0fiHHi0DLRr/0KNloEXjH3q0DLRo/EOPloEWjX/o0TLQovEPPVoGWjT%2BoUfLQIvGP/RoGWjR%2BIceJQMPIOzeGc0PIDEAAAAASUVORK5CYII";
+}, "<img> fetch that redirects to data: URL");
+
+globalThis.globalTest = null;
+async_test(t => {
+  globalThis.globalTest = t;
+  const script = document.createElement("script");
+  script.src = "../api/resources/redirect.py?location=data:text/javascript,(globalThis.globalTest.unreached_func())()";
+  script.onerror = t.step_func_done();
+  document.body.append(script);
+}, "<script> fetch that redirects to data: URL");
+
+promise_test(t => {
+  return promise_rejects_js(t, TypeError, fetch("../api/resources/redirect.py?location=data:,"));
+}, "fetch() fetch that redirects to data: URL");
+
+async_test(t => {
+  const client = new XMLHttpRequest();
+  client.open("GET", "../api/resources/redirect.py?location=data:,");
+  client.send();
+  client.onload = t.unreached_func();
+  client.onerror = t.step_func_done();
+}, "XMLHttpRequest fetch that redirects to data: URL");