MD Settings: long dialog body should have overscroll line.

chrome/browser/resources/settings/passwords_and_forms_page/address_edit_dialog.html

 <link rel="import" href="chrome://resources/cr_elements/cr_dialog/cr_dialog.html">
+<link rel="import" href="chrome://resources/cr_elements/cr_scrollable_behavior.html">
 <link rel="import" href="chrome://resources/html/cr.html">
 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
 <link rel="import" href="chrome://resources/html/md_select_css.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-a11y-keys/iron-a11y-keys.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-input.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-textarea.html">
 <link rel="import" href="../settings_shared_css.html">
 <link rel="import" href="../settings_vars_css.html">
 
@@ skipping 34 matching lines @@
 
       #dialog .body {
         max-height: 450px;
       }
 
       @media all and (max-height: 714px) {
         #dialog .body {
           max-height: 270px;
         }
       }
+
+      [scrollable].is-scrolled {
+        border-top-color: transparent;

[scottchen, 2017/02/17 22:40:04]

This is to prevent double-border, since the dialog title already has a top
border all the time.

+      }
     </style>
     <dialog is="cr-dialog" id="dialog">
       <div class="title">[[title_]]</div>
-      <div class="body">
+      <div class="body" scrollable>
         <template is="dom-repeat" items="[[addressWrapper_]]">
           <div class="address-row">
             <template is="dom-repeat" items="[[item]]">
               <template is="dom-if" if="[[item.isTextArea]]">
                 <paper-textarea label="[[item.component.fieldName]]"
                     value="{{item.value}}" on-value-changed="updateCanSave_"
                     class$="address-column [[long_(item)]]" always-float-label>
                 </paper-textarea>
               </template>
               <template is="dom-if" if="[[!item.isTextArea]]">
@@ skipping 45 matching lines @@
         </paper-button>
         <paper-button id="saveButton" class="action-button"
             disabled="[[!canSave_]]" on-tap="onSaveButtonTap_">
           $i18n{save}
         </paper-button>
       </div>
     </dialog>
   </template>
   <script src="address_edit_dialog.js"></script>
 </dom-module>