WebUI: Fix cr-action-menu opening outside of layout.

ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 Polymer({
   is: 'cr-action-menu',
   extends: 'dialog',
 
   /**
    * List of all options in this action menu.
@@ skipping 155 matching lines @@
         this.close();
     }.bind(this);
     window.addEventListener('resize', this.boundClose_);
     window.addEventListener('popstate', this.boundClose_);
 
     // Reset position to prevent previous values from affecting layout.
     this.style.left = '';
     this.style.right = '';
     this.style.top = '';
 
+    this.anchorElement_.scrollIntoViewIfNeeded();
     this.showModal();
 
     var rect = this.anchorElement_.getBoundingClientRect();
     if (getComputedStyle(this.anchorElement_).direction == 'rtl') {
       var right = window.innerWidth - rect.left - this.offsetWidth;
       this.style.right = right + 'px';
     } else {
       var left = rect.right - this.offsetWidth;
       this.style.left = left + 'px';
     }
 
     // Attempt to show the menu starting from the top of the rectangle and
     // extending downwards. If that does not fit within the window, fallback to
     // starting from the bottom and extending upwards.
     var top = rect.top + this.offsetHeight <= window.innerHeight ? rect.top :
                                                                    rect.bottom -
             this.offsetHeight - Math.max(rect.bottom - window.innerHeight, 0);
 
     this.style.top = top + 'px';
   },
 });