Fix autofocus in FF

/cc @jonrohan

Author: josh

jquery.pjax.js

@@ -263,6 +263,17 @@ function pjax(options) {
 
     if (container.title) document.title = container.title
     context.html(container.contents)
+
+    // FF bug: Won't autofocus fields that are inserted via JS.
+    // This behavior is incorrect. So if theres no current focus, autofocus
+    // the last field.
+    //
+    // http://www.w3.org/html/wg/drafts/html/master/forms.html
+    var autofocusEl = context.find('input[autofocus], textarea[autofocus]').last()[0]
+    if (autofocusEl && document.activeElement !== autofocusEl) {
+      autofocusEl.focus();
+    }
+
     executeScriptTags(container.scripts)
 
     // Scroll to top by default