JS: Add test

Author: asgerf

javascript/ql/test/query-tests/Security/CWE-079/DomBasedXss/dom.js

@@ -0,0 +1,5 @@
+function t1() {
+    const elm = document.getElementById("foo");
+    const e2 = elm.getElementsByTagName("bar")[0];
+    e2.innerHTML = window.name; // $ MISSING: Alert
+}