Allow on-* event handlers on <sky-element>.

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

Index: sky/framework/sky-radio/sky-radio.sky
diff --git a/sky/framework/sky-radio/sky-radio.sky b/sky/framework/sky-radio/sky-radio.sky
index 7b759d5e954cb21deab75ca0d75d8fb747bf6391..011f0d3f745593461803f560936b2451bc21aaf7 100644
--- a/sky/framework/sky-radio/sky-radio.sky
+++ b/sky/framework/sky-radio/sky-radio.sky
@@ -5,7 +5,10 @@
 -->
 <import src="/sky/framework/sky-button/sky-button.sky" as="SkyButton" />
 
-<sky-element name="sky-radio" attributes="selected:boolean, group:string">
+<sky-element
+    name="sky-radio"
+    attributes="selected:boolean, group:string"
+    on-mouseup="handleMouseUp">
 <template>
   <style>
     :host {
@@ -75,10 +78,6 @@ module.exports = class extends SkyButton {
     super.created();
 
     this.controller = null;
-
-    this.addEventListener('mouseup', function() {
-      this.selected = true;
-    });
   }
   attached() {
     super.attached();
@@ -98,6 +97,9 @@ module.exports = class extends SkyButton {
     if (this.selected && this.controller)
       this.controller.takeSelectionFromGroup(this);
   }
+  handleMouseUp() {
+    this.selected = true;
+  }
 }.register();
 </script>
 </sky-element>