Fix clear button element id.

dependency-examples/emberjs_require/js/app/templates/clear_button.html

 {{#with view}}
-	<button {{action "clearCompleted" target="entries"}} >
+	<button id="clear-completed" {{action "clearCompleted" target="entries"}} >
 		Clear completed ({{entries.completed}})
 	</button>
 {{/with}}

dependency-examples/emberjs_require/js/app/views/clear_button.js

@@ -12,7 +12,6 @@ define('app/views/clear_button', [
 		return Ember.View.extend({
 			entriesBinding: 'controller.namespace.entriesController',
 			template: Ember.Handlebars.compile( button_html ),
-			elementId: 'clear-completed',
 			classNameBindings: 'buttonClass',
 			buttonClass: function () {
 				if ( !this.getPath( 'entries.completed' ) )