createEvent should increase tag count by 1

src/tests/dom/document.html

@@ -60,7 +60,7 @@
   let byTagNameAll = document.getElementsByTagName('*');
   // If you add a script block (or change the HTML in any other way on this
   // page), this test will break. Adjust it accordingly.
-  testing.expectEqual(20, byTagNameAll.length);
+  testing.expectEqual(21, byTagNameAll.length);
   testing.expectEqual('html', byTagNameAll.item(0).localName);
   testing.expectEqual('SCRIPT', byTagNameAll.item(11).tagName);