Upgrade to 1.0 and switch clients to dom-repeat where needed.

third_party/polymer/v0_8/components/iron-collapse/iron-collapse.html

 <!--
 @license
 Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
 This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
 The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
 The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
 Code distributed by Google as part of the polymer project is also
 subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 -->
 
@@ skipping 25 matching lines @@
         border: 1px solid #dedede;
       }
     </style>
 
     <iron-collapse>
       <div class="collapse-content">
         <div>Content goes here...</div>
       </div>
     </iron-collapse>
 
-@group Polymer Core Elements
+@group Iron Elements
+@hero hero.svg
+@demo demo/index.html
 @element iron-collapse
 -->
 
 <dom-module id="iron-collapse">
 
   <style>
 
     :host {
       display: block;
       transition-duration: 300ms;
@@ skipping 22 matching lines @@
   Polymer({
 
     is: 'iron-collapse',
 
     properties: {
 
       /**
        * If true, the orientation is horizontal; otherwise is vertical.
        *
        * @attribute horizontal
-       * @type Boolean
-       * @default false
        */
       horizontal: {
         type: Boolean,
         value: false,
-        observer: 'horizontalChanged'
+        observer: '_horizontalChanged'
       },
 
       /**
        * Set opened to true to show the collapse element and to false to hide it.
        *
        * @attribute opened
-       * @type Boolean
-       * @default false
        */
       opened: {
         type: Boolean,
         value: false,
         notify: true,
-        observer: 'openedChanged'
+        observer: '_openedChanged'
       }
 
     },
 
+    hostAttributes: {
+      role: 'group',
+      'aria-expanded': 'false',
+      tabindex: 0
+    },
+
     listeners: {
-      transitionend: 'transitionEnd'
+      transitionend: '_transitionEnd'
     },
 
     ready: function() {
       // Avoid transition at the beginning e.g. page loads and enable
       // transitions only after the element is rendered and ready.
       this._enableTransition = true;
     },
 
-    horizontalChanged: function() {
-      this.dimension = this.horizontal ? 'width' : 'height';
-      this.style.transitionProperty = this.dimension;
-    },
-
-    openedChanged: function() {
-      this[this.opened ? 'show' : 'hide']();
-    },
-
     /**
      * Toggle the opened state.
      *
      * @method toggle
      */
     toggle: function() {
       this.opened = !this.opened;
     },
 
     show: function() {
       this.toggleClass('iron-collapse-closed', false);
       this.updateSize('auto', false);
-      var s = this.calcSize();
+      var s = this._calcSize();
       this.updateSize('0px', false);
       // force layout to ensure transition will go
       this.offsetHeight;
       this.updateSize(s, true);
     },
 
     hide: function() {
       this.toggleClass('iron-collapse-opened', false);
-      this.updateSize(this.calcSize(), false);
+      this.updateSize(this._calcSize(), false);
       // force layout to ensure transition will go
       this.offsetHeight;
       this.updateSize('0px', true);
     },
 
     updateSize: function(size, animated) {
       this.enableTransition(animated);
       var s = this.style;
       var nochange = s[this.dimension] === size;
       s[this.dimension] = size;
       if (animated && nochange) {
-        this.transitionEnd();
+        this._transitionEnd();
       }
     },
 
-    calcSize: function() {
-      return this.getBoundingClientRect()[this.dimension] + 'px';
-    },
-
     enableTransition: function(enabled) {
       this.style.transitionDuration = (enabled && this._enableTransition) ? '' : '0s';
     },
 
-    transitionEnd: function() {
+    _horizontalChanged: function() {
+      this.dimension = this.horizontal ? 'width' : 'height';
+      this.style.transitionProperty = this.dimension;
+    },
+
+    _openedChanged: function() {
+      this[this.opened ? 'show' : 'hide']();
+      this.setAttribute('aria-expanded', this.opened ? 'true' : 'false');
+
+    },
+
+    _transitionEnd: function() {
       if (this.opened) {
         this.updateSize('auto', false);
       }
       this.toggleClass('iron-collapse-closed', !this.opened);
       this.toggleClass('iron-collapse-opened', this.opened);
       this.enableTransition(false);
-    }
+    },
+
+    _calcSize: function() {
+      return this.getBoundingClientRect()[this.dimension] + 'px';
+    },
+
 
   });
 
 </script>