Roll third_party/polymer.

third_party/polymer/v1_0/components-chromium/iron-collapse/iron-collapse-extracted.js

 Polymer({
 
     is: 'iron-collapse',
 
     behaviors: [
       Polymer.IronResizableBehavior
     ],
 
     properties: {
 
@@ skipping 68 matching lines @@
     },
 
     updateSize: function(size, animated) {
       // No change!
       if (this.style[this.dimension] === size) {
         return;
       }
 
       this._updateTransition(false);
       // If we can animate, must do some prep work.
-      if (animated && !this.noAnimation) {
+      if (animated && !this.noAnimation && this._isDisplayed) {
         // Animation will start at the current size.
         var startSize = this._calcSize();
         // For `auto` we must calculate what is the final size for the animation.
         // After the transition is done, _transitionEnd will set the size back to `auto`.
         if (size === 'auto') {
           this.style[this.dimension] = size;
           size = this._calcSize();
         }
         // Go to startSize without animation.
         this.style[this.dimension] = startSize;
@@ skipping 50 matching lines @@
     _transitionEnd: function() {
       if (this.opened) {
         this.style[this.dimension] = 'auto';
       }
       this.toggleClass('iron-collapse-closed', !this.opened);
       this.toggleClass('iron-collapse-opened', this.opened);
       this._updateTransition(false);
       this.notifyResize();
     },
 
+    /**
+     * Simplistic heuristic to detect if element has a parent with display: none
+     *
+     * @private
+     */
+    get _isDisplayed() {
+      var rect = this.getBoundingClientRect();
+      for (var prop in rect) {
+        if (rect[prop] !== 0) return true;
+      }
+      return false;
+    },
+
     _calcSize: function() {
       return this.getBoundingClientRect()[this.dimension] + 'px';
     }
 
   });