Fix download button

Author: mdboom

lib/matplotlib/backends/web_backend/mpl.js

@@ -193,7 +193,7 @@ mpl.figure.prototype._init_toolbar = function() {
     fmt_picker.addClass('mpl-toolbar-option ui-widget ui-widget-content');
     fmt_picker_span.append(fmt_picker);
     nav_element.append(fmt_picker_span);
-    this.format_dropdown = fmt_picker;
+    this.format_dropdown = fmt_picker[0];
 
     for (var ind in mpl.extensions) {
         var fmt = mpl.extensions[ind];