MD WebUI: Use dom-if to control hidden elements in <cr-toolbar>

ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-input/iron-input.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-input-container.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-spinner/paper-spinner-lite.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_search_field/cr_search_field_behavior.html">
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 
 <dom-module id="cr-toolbar-search-field">
   <template>
@@ skipping 94 matching lines @@
 
       :host([narrow][showing-search]) {
         width: 100%;
       }
 
       :host([narrow][showing-search]) #icon,
       :host([narrow][showing-search]) paper-spinner-lite {
         -webkit-margin-start: 18px;
       }
     </style>
-    <paper-spinner-lite
-        active="[[isSpinnerShown_(spinnerActive, showingSearch)]]">
-    </paper-spinner-lite>
+    <template is="dom-if" if="[[isSpinnerShown_]]">
+      <paper-spinner-lite active>
+      </paper-spinner-lite>
+    </template>
     <paper-icon-button id="icon" icon="cr:search" title="[[label]]"
         tabindex$="[[computeIconTabIndex_(narrow)]]">
     </paper-icon-button>
     <paper-input-container id="searchTerm" on-search="onSearchTermSearch"
         on-keydown="onSearchTermKeydown" no-label-float>
       <label id="prompt" for="searchInput">[[label]]</label>
       <input is="iron-input" id="searchInput" type="search"
           on-blur="onInputBlur_" incremental autofocus></input>
     </paper-input-container>
-    <paper-icon-button icon="cr:cancel" id="clearSearch"
-        title="[[clearLabel]]" hidden$="[[!hasSearchText_]]"
-        on-tap="hideSearch_">
-    </paper-icon-button>
+    <template is="dom-if" if="[[hasSearchText_]]">
+      <paper-icon-button icon="cr:cancel" id="clearSearch"
+          title="[[clearLabel]]" on-tap="hideSearch_">
+      </paper-icon-button>
+    </template>
   </template>
   <script src="cr_toolbar_search_field.js"></script>
 </dom-module>