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

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

Index: ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.js
diff --git a/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.js b/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.js
index 86fe5aa484f39a69dfe6a572f107f1f75136a63c..e85c23fd29c6c92a91da6fcf98293560cdbe4d13 100644
--- a/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.js
+++ b/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.js
@@ -29,6 +29,11 @@ Polymer({
 
     /** @private */
     hasSearchText_: Boolean,
+
+    isSpinnerShown_: {
+      type: Boolean,
+      computed: 'computeIsSpinnerShown_(spinnerActive, showingSearch)'
+    }
   },
 
   listeners: {
@@ -56,13 +61,11 @@ Polymer({
   },
 
   /**
-   * @param {boolean} spinnerActive
-   * @param {boolean} showingSearch
    * @return {boolean}
    * @private
    */
-  isSpinnerShown_: function(spinnerActive, showingSearch) {
-    return spinnerActive && showingSearch;
+  computeIsSpinnerShown_: function() {
+    return this.spinnerActive && this.showingSearch;
   },
 
   /** @private */