MD WebUI: Make cr-lazy-render get() synchronous

ui/webui/resources/cr_elements/cr_lazy_render/cr_lazy_render.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview
  * cr-lazy-render is a simple variant of dom-if designed for lazy rendering
  * of elements that are accessed imperatively.
  * Usage:
  *   <template is="cr-lazy-render" id="menu">
  *     <heavy-menu></heavy-menu>
  *   </template>
  *
- *   this.$.menu.get().then(function(menu) {
- *     menu.show();
- *   });
+ *   this.$.menu.get().show();
  */
 
 Polymer({
   is: 'cr-lazy-render',
   extends: 'template',
 
   behaviors: [
     Polymer.Templatizer
   ],
 
-  /** @private {Promise<Element>} */
-  renderPromise_: null,
-
   /** @private {TemplatizerNode} */
   child_: null,
 
   /**
-   * Stamp the template into the DOM tree asynchronously
-   * @return {Promise<Element>} Promise which resolves when the template has
-   *   been stamped.
+   * Stamp the template into the DOM tree synchronously
+   * @return {Element} Child element which has been stamped into the DOM tree.
    */
   get: function() {
-    if (!this.renderPromise_) {
-      this.renderPromise_ = new Promise(function(resolve) {
-        this._debounceTemplate(function() {
-          this.render_();
-          this.renderPromise_ = null;
-          resolve(this.getIfExists());
-        }.bind(this));
-      }.bind(this));
-    }
-    return this.renderPromise_;
+    if (!this.child_)
+      this.render_();
+    return this.child_;
   },
 
   /**
    * @return {?Element} The element contained in the template, if it has
    *   already been stamped.
    */
   getIfExists: function() {
     return this.child_;
   },
 
@@ skipping 20 matching lines @@
 
   /**
    * @param {string} path
    * @param {Object} value
    */
   _forwardParentPath: function(path, value) {
     if (this.child_)
       this.child_._templateInstance.notifyPath(path, value, true);
   }
 });