LayoutBox::scrollRectToVisible doesn't respect overflow:hidden property.

third_party/WebKit/Source/core/css/html.css

 /*
  * The default style sheet used to render HTML.
  *
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 508 matching lines @@
     -webkit-rtl-ordering: logical;
     -webkit-user-select: text;
     flex-direction: column;
     resize: auto;
     cursor: auto;
     padding: 2px;
     white-space: pre-wrap;
     word-wrap: break-word;
 }
 
+input:not([type])::-webkit-scrollbar,
+input[type="email"]::-webkit-scrollbar,
+input[type="number"]::-webkit-scrollbar,
+input[type="password"]::-webkit-scrollbar,
+input[type="search"]::-webkit-scrollbar,
+input[type="telephone"]::-webkit-scrollbar,
+input[type="text"]::-webkit-scrollbar,
+input[type="url"]::-webkit-scrollbar {
+    display:none;
+}
+
 ::-webkit-input-placeholder {
     -webkit-text-security: none;
     color: darkGray;
     pointer-events: none !important;
 }
 
 input::-webkit-input-placeholder {
     white-space: pre;
     word-wrap: normal;
     overflow: hidden;
@@ skipping 425 matching lines @@
     vertical-align: super;
     font-size: smaller
 }
 
 nobr {
     white-space: nowrap
 }
 
 /* states */
 
-:focus { 
+:focus {
     outline: auto 5px -webkit-focus-ring-color
 }
 
 /* Read-only text fields do not show a focus ring but do still receive focus */
-html:focus, body:focus, input[readonly]:focus { 
+html:focus, body:focus, input[readonly]:focus {
     outline: none
 }
 
 embed:focus, iframe:focus, object:focus {
     outline: none
 }
-  
+
 input:focus, textarea:focus, keygen:focus, select:focus {
     outline-offset: -2px
 }
 
 input[type="button" i]:focus,
 input[type="checkbox" i]:focus,
 input[type="file" i]:focus,
 input[type="hidden" i]:focus,
 input[type="image" i]:focus,
 input[type="radio" i]:focus,
 input[type="reset" i]:focus,
 input[type="search" i]:focus,
 input[type="submit" i]:focus,
 input[type="file" i]:focus::-webkit-file-upload-button {
     outline-offset: 0
 }
-    
+
 a:-webkit-any-link {
     color: -webkit-link;
     text-decoration: underline;
     cursor: auto;
 }
 
 a:-webkit-any-link:active {
     color: -webkit-activelink
 }
 
@@ skipping 104 matching lines @@
 }
 
 /* Disable multicol in printing, since it's not implemented properly. See crbug.com/99358 */
 
 @media print {
     * { -webkit-columns: auto !important; }
 }
 
 /* noscript is handled internally, as it depends on settings. */