Switch Sky to pointer events

sky/framework/sky-radio/sky-radio.sky

 <!--
 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 -->
 <import src="/sky/framework/sky-button/sky-button.sky" as="SkyButton" />
 
 <sky-element
     name="sky-radio"
     attributes="selected:boolean, group:string"
-    on-mouseup="handleMouseUp">
+    on-click="handleClick">
 <template>
   <style>
     :host {
       display: inline-block;
       -webkit-user-select: none;
       width: 14px;
       height: 14px;
       border-radius: 7px;
       border: 1px solid blue;
       margin: 0 5px;
@@ skipping 68 matching lines @@
     this.controller = null;
   }
   selectedChanged(oldValue, newValue) {
     if (newValue && this.controller)
       this.controller.takeSelectionFromGroup(this);
   }
   groupChanged(oldValue, newValue) {
     if (this.selected && this.controller)
       this.controller.takeSelectionFromGroup(this);
   }
-  handleMouseUp() {
+  handleClick() {
     this.selected = true;
   }
 }.register();
 </script>
 </sky-element>