Material PDF: Fix inconsistent behaviour in page selector, update styling

chrome/browser/resources/pdf/elements/viewer-pdf-toolbar/viewer-pdf-toolbar.js

 // 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.
 (function() {
   Polymer({
     is: 'viewer-pdf-toolbar',
 
     properties: {
       /**
        * The current loading progress of the PDF document (0 - 100).
        */
       loadProgress: {
         type: Number,
         observer: 'loadProgressChanged'
       },
 
       /**
        * The title of the PDF document.
        */
       docTitle: String,
 
       /**
-       * The current index of the page being viewed (0-based).
+       * The number of the page being viewed (1-based).
        */
-      pageIndex: Number,
+      pageNo: Number,
 
       /**
        * Whether the document has bookmarks.
        */
       hasBookmarks: Boolean,
 
       /**
        * The number of pages in the PDF document.
        */
       docLength: Number,
@@ skipping 45 matching lines @@
 
     save: function() {
       this.fire('save');
     },
 
     print: function() {
       this.fire('print');
     }
   });
 })();