toggle scroll from auto based on current scroll

rather than always `false`

IPython/html/static/notebook/js/outputarea.js

@@ -188,7 +188,7 b' define(['
 
     OutputArea.prototype.toggle_scroll = function () {
         if (this.scroll_state == 'auto') {
-            this.scroll_state = false;
+            this.scroll_state = !this.scrolled;
         } else {
             this.scroll_state = !this.scroll_state;
         }