MD Settings: long dialog body should have overscroll line.

chrome/browser/resources/settings/languages_page/add_languages_dialog.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.
 
 /**
  * @fileoverview 'settings-add-languages-dialog' is a dialog for enabling
  * languages.
  */
 Polymer({
   is: 'settings-add-languages-dialog',
 
+  behaviors: [
+    CrScrollableBehavior,
+  ],
+
   properties: {
     /** @type {!LanguagesModel|undefined} */
     languages: {
       type: Object,
       notify: true,
     },
 
     /** @type {!LanguageHelper} */
     languageHelper: Object,
 
     /** @private {!Set<string>} */
     languagesToAdd_: {
       type: Object,
-      value: function() { return new Set(); },
+      value: function() {
+        return new Set();
+      },
     },
 
     /** @private */
     disableActionButton_: {
       type: Boolean,
       value: true,
     },
 
     /** @private */
     filterValue_: {
@@ skipping 35 matching lines @@
           this.filterValue_.toLowerCase());
     }.bind(this));
   },
 
   /**
    * @param {!chrome.languageSettingsPrivate.Language} language
    * @return {string} The text to be displayed.
    * @private
    */
   getDisplayText_: function(language) {
-     var displayText = language.displayName;
-     // If the native name is different, add it.
-     if (language.displayName != language.nativeDisplayName)
-       displayText += ' - ' + language.nativeDisplayName;
-     return displayText;
+    var displayText = language.displayName;
+    // If the native name is different, add it.
+    if (language.displayName != language.nativeDisplayName)
+      displayText += ' - ' + language.nativeDisplayName;
+    return displayText;
   },
 
   /**
    * True if the user has chosen to add this language (checked its checkbox).
    * @param {string} languageCode
    * @return {boolean}
    * @private
    */
   willAdd_: function(languageCode) {
     return this.languagesToAdd_.has(languageCode);
@@ skipping 28 matching lines @@
    * Enables the checked languages.
    * @private
    */
   onActionButtonTap_: function() {
     this.$.dialog.close();
     this.languagesToAdd_.forEach(function(languageCode) {
       this.languageHelper.enableLanguage(languageCode);
     }.bind(this));
   },
 });