[polymer] import all elements

pkg/polymer/lib/elements/polymer-animation/polymer-animation-prop.html

+<link rel="import" href="../polymer/polymer.html">
+
+<polymer-element name="polymer-animation-prop" attributes="name value">
+  <script>
+    /**
+     * A CSS property and value to use in a `<polymer-animation-keyframe>`.
+     *
+     * @class polymer-animation-prop
+     */
+                /**
+                 * CSS property name.
+                 * @property name
+                 * @type String
+                 * @required
+                 */
+     /**
+      * CSS property value.
+      * @property value
+      * @required
+      */
+      Polymer('polymer-animation-prop');
+  </script>
+</polymer-element>