1 files changed, 26 insertions, 0 deletions
diff --git a/dom/tests/mochitest/webcomponents/head.js b/dom/tests/mochitest/webcomponents/head.js
new file mode 100644
index 0000000000..23c91d63be
--- /dev/null
+++ b/dom/tests/mochitest/webcomponents/head.js
@@ -0,0 +1,26 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+/**
+ * Loads an iframe.
+ *
+ * @return {Promise} promise that resolves when iframe is loaded.
+ */
+function createIframe(aSrcDoc) {
+  return new Promise(function (aResolve, aReject) {
+    let iframe = document.createElement("iframe");
+    iframe.onload = function () {
+      aResolve(iframe.contentDocument);
+    };
+    iframe.onerror = function () {
+      aReject("Failed to load iframe");
+    };
+    if (aSrcDoc) {
+      iframe.srcdoc = aSrcDoc;
+    }
+    document.body.appendChild(iframe);
+  });
+}