[MD Extensions] Add newlines between style rules in HTML

chrome/browser/resources/md_extensions/keyboard_shortcuts.html

 <link rel="import" href="chrome://resources/html/cr.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/neon-animatable-behavior.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-dropdown-menu/paper-dropdown-menu.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-item/paper-item.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-listbox/paper-listbox.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/color.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/shadow.html">
 <link rel="import" href="chrome://extensions/animation_helper.html">
 <link rel="import" href="chrome://extensions/shortcut_input.html">
 
 <dom-module id="extensions-keyboard-shortcuts">
   <template>
     <style>
       [hidden] {
         display: none !important;
       }
+
       .shortcut-card {
         @apply(--shadow-elevation-2dp);
         background-color: white;
         color: var(--paper-grey-600);
         margin-bottom: 10px;
         padding: 20px;
         width: 90%;
       }
+
       .command-entry {
         align-items: flex-end;
         display: flex;
       }
+
       .command-name {
         flex: 1;
       }
+
       .command-entry paper-dropdown-menu {
         -webkit-margin-start: 40px;
       }
+
       .card-title {
         align-items: center;
         display: flex;
       }
+
       .icon {
         -webkit-margin-end: 20px;
         height: 24px;
         width: 24px;
       }
+
       .card-controls {
         /* We line up the controls with the name, which is after the
            24px icon + 20px margin on the icon. */
         -webkit-margin-start: 44px;
       }
     </style>
     <div id="main">
       <template is="dom-repeat" items="[[calculateShownItems_(items.*)]]">
         <div class="shortcut-card">
           <div class="card-title">
@@ skipping 17 matching lines @@
                 </paper-dropdown>
               </div>
             </template>
           </div>
         </div>
       </template>
     </div>
   </template>
   <script src="chrome://extensions/keyboard_shortcuts.js"></script>
 </dom-module>