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

third_party/polymer/v0_8/components-chromium/iron-collapse/README.md

 # iron-collapse
+
+`iron-collapse` creates a collapsible block of content.  By default, the content
+will be collapsed.  Use `opened` or `toggle()` to show/hide the content.
+
+```html
+<button on-click="{{toggle}}">toggle collapse</button>
+
+<iron-collapse id="collapse">
+  <div>Content goes here...</div>
+</iron-collapse>
+```
+
+```javascript
+toggle: function() {
+  this.$.collapse.toggle();
+}
+```
+
+`iron-collapse` adjusts the height/width of the collapsible element to show/hide
+the content.  So avoid putting padding/margin/border on the collapsible directly,
+and instead put a div inside and style that.
+
+```html
+<style>
+  .collapse-content {
+    padding: 15px;
+    border: 1px solid #dedede;
+  }
+</style>
+
+<iron-collapse>
+  <div class="collapse-content">
+    <div>Content goes here...</div>
+  </div>
+</iron-collapse>
+```