Material PDF: Support RTL languages

chrome/browser/resources/pdf/elements/viewer-page-selector/viewer-page-selector.css

 /* Copyright 2015 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. */
 
 :host {
   color: #fff;
   font-size: 88.8%;
 }
 
 #pageselector {
   --paper-input-container-underline: {
     visibility: hidden;
   };
   --paper-input-container-underline-focus: {
     visibility: hidden;
   };
   display: inline-block;
   padding: 0;
   width: 1ch;
 }
 
 input#input {
+  -webkit-margin-start: -3px;
   color: #fff;
   line-height: 18px;
-  margin-left: -3px;
   padding: 3px;
-  text-align: right;
+  text-align: end;
 }
 
 input#input:focus,
 input#input:hover {
   background-color: rgba(0, 0, 0, 0.5);
   border-radius: 2px;
 }
 
-input::-webkit-outer-spin-button,
-input::-webkit-inner-spin-button {
-  -webkit-appearance: none;
-  margin: 0;
-}
-
 #slash {
   padding: 0 3px;
 }
 
 #pagelength-spacer {
   display: inline-block;
-  text-align: left;
+  text-align: start;
 }
 
 #slash,
 #pagelength {
   font-size: 81.25%;
 }