Update bower.json for Polymer elements and add PRESUBMIT.py

third_party/web-animations-js/sources/History.md

+### 2.1.2 - *July 8 2015*
+  * Fix a bug where onfinish was being called for GroupEffects before they were finished.
+
+### 2.1.1 - *July 1 2015*
+  * Add Animation.timeline getter
+  * Add AnimationEffect.parent getter
+  * Make AnimationEffectTiming (returned by AnimationEffect.timing) attributes mutable
+  * Expose the Animation constructor
+  * Change custom effects from AnimationEffects to onsample functions. Custom effects should now be created by setting the onsample attribute of a KeyframeEffect.
+
+    For example, this is deprecated:
+
+        var myEffect = new KeyframeEffect(
+           element,
+           function(timeFraction, target, effect) {
+              target.style.opacity = timeFraction;
+           },
+           1000);
+        var myAnimation = document.timeline.play(myEffect);
+
+    and this should be used insead:
+
+        var myEffect = new KeyframeEffect(element, [], 1000);
+        effect.onsample = function(timeFraction, effect, animation) {
+           effect.target.style.opacity = timeFraction;
+        };
+        var myAnimation = document.timeline.play(myEffect);
+
 ### 2.1.0 - *June 15 2015*
   * Fix bug affecting GroupEffects with infinite iteration children
   * Add GroupEffect.firstChild and GroupEffect.lastChild
   * Add initial values for most CSS properties
   * Allow `timeline.play()` to be called with no arguments
   * Add AnimationEffect.clone
   * Add GroupEffect.append and GroupEffect.prepend
   * Add AnimationEffect.remove
   * Add Animation.ready and Animation.finished promises
 
@@ skipping 98 matching lines @@
 
   `web-animations-next-lite.min.js` - A cut down version of
   web-animations-next, removes several lesser used property handlers
   and some of the larger and less used features such as matrix
   interpolation/decomposition.
 
   Not all features of the previous polyfill have been ported to the
   new codebase; most notably mutation of Animations and Groups and
   Additive Animations are not yet supported. These features are still
   important and will be implemented in the coming weeks.