history: Fix navigation when entering a repeat

If the user typed "a", hit up, and pressed enter again, we wouldn't re-set the
history pointer to the end, so the broken navigation would instead go to the
entry before that.

https://bugzilla.gnome.org/show_bug.cgi?id=648765

js/misc/history.js

@@ -77,9 +77,9 @@ HistoryManager.prototype = {
             this._history[this._history.length - 1] != input) {
 
             this._history.push(input);
-            this._historyIndex = this._history.length;
             this._save();
         }
+        this._historyIndex = this._history.length;
     },
 
     _onEntryKeyPress: function(entry, event) {