Fix PerformanceResourceTiming transferSize field for sync XHR

third_party/WebKit/LayoutTests/http/tests/misc/resources/resource-timing-sizes-sync-xhr-transfer-size.js

+// This test code is shared between
+// resource-timing-sizes-sync-xhr-transfer-size.html and
+// resource-timing-sizes-sync-xhr-transfer-size-worker.html
+
+if (typeof document === 'undefined') {
+  importScripts('/resources/testharness.js');
+}
+
+const minSize = 100;
+const url = new URL(cacheBust('/resources/dummy.xml'), location.href).href;
+var t = async_test('PerformanceResourceTiming sync XHR transferSize test');
+
+function cacheBust(url) {
+  return url + '?bust=' + Math.random().toString().substring(2);
+}
+
+function check() {
+  var entries = performance.getEntriesByName(url);
+  assert_equals(entries.length, 1, 'entries.length');
+  var entry = entries[0];
+  assert_greater_than(entry.transferSize, minSize, 'transferSize');
+  t.done();
+}
+
+function run() {
+  var xhr = new XMLHttpRequest();
+  xhr.open('GET', url, false);
+  xhr.send();
+  setTimeout(t.step_func(check), 0);
+}
+
+run();
+
+done();