diff --git a/mercurial/templates/static/mercurial.js b/mercurial/templates/static/mercurial.js
--- a/mercurial/templates/static/mercurial.js
+++ b/mercurial/templates/static/mercurial.js
@@ -328,3 +328,9 @@ function makeRequest(url, method, onstar
     onstart();
     return xfr;
 }
+
+function docFromHTML(html) {
+    var doc = document.implementation.createHTMLDocument('');
+    doc.documentElement.innerHTML = html;
+    return doc;
+}