MD Settings: Stop rendering unnecessary iron-collapse instances in cert manager.

chrome/browser/resources/settings/certificate_manager_page/certificate_entry.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_expand_button/cr_expand_button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-collapse/iron-collapse.html">
 <link rel="import" href="certificates_browser_proxy.html">
 <link rel="import" href="../settings_shared_css.html">
 <link rel="import" href="certificate_subentry.html">
 
 <dom-module id="settings-certificate-entry">
   <template>
     <style include="settings-shared"></style>
     <div class="settings-box">
       <div class="start">[[model.id]]</div>
       <cr-expand-button expanded="{{expanded_}}"
           alt="$i18n{certificateManagerExpandA11yLabel}">
       </cr-expand-button>
     </div>
-    <iron-collapse opened="[[expanded_]]" no-animation>
-      <template is="dom-if" if="[[expanded_]]">
+    <template is="dom-if" if="[[expanded_]]">

[dpapad, 2017/04/05 00:36:39]

Moving the dom-if outside the iron-collapse saves about 100+ iron-collapse
elements which used to be rendered when the "Authorities" tab was clicked. Now
each one of them is renedred only if the user requests it.

+      <iron-collapse opened="[[expanded_]]" no-animation>

[dpapad, 2017/04/05 00:36:39]

We our using no-animation for our iron-collapse, which essentially makes it a
completely unnecessary wrapper around the list-frame div below. We should
probably remove this completely in a follow up CL.

         <div class="list-frame">
           <template is="dom-repeat" items="[[model.subnodes]]">
             <settings-certificate-subentry model="[[item]]"
                 certificate-type="[[certificateType]]"
                 is-last$="[[isLast_(index, model)]]">
             </settings-certificate-subentry>
           </template>
         </div>
-      </template>
-    <iron-collapse>
+      <iron-collapse>
+    </template>
   </template>
   <script src="certificate_entry.js"></script>
 </dom-module>