Fix resource clean up in TemplateIterator.close()

sky/framework/sky-element/sky-binder.sky

Index: sky/framework/sky-element/sky-binder.sky
diff --git a/sky/framework/sky-element/sky-binder.sky b/sky/framework/sky-element/sky-binder.sky
index a67861de4d7c72d3419f2c3b6af55b2ae86ec093..7a7914c544f31c60905f44a1f147dafa001a3d11 100644
--- a/sky/framework/sky-element/sky-binder.sky
+++ b/sky/framework/sky-element/sky-binder.sky
@@ -455,10 +455,10 @@ class TemplateIterator {
 
     this.instances.length = 0;
 
-    if (this.ifBinding)
-      this.ifBinding.close();
-    if (this.binding)
-      this.binding.close();
+    if (this.ifObserver)
+      this.ifObserver.close();
+    if (this.valueObserver)
+      this.valueObserver.close();
 
     iterators.delete(this.template);
     this.closed = true;