Replace createTextNode with new Text().

sky/tests/mutation-observer/shadow-dom.sky

Index: sky/tests/mutation-observer/shadow-dom.sky
diff --git a/sky/tests/mutation-observer/shadow-dom.sky b/sky/tests/mutation-observer/shadow-dom.sky
index f2d1f49b28814a63cbd6ad82241307af9b0cdf33..9be869decd9d7c09adf1bc0a0703c924bd4f1f7c 100644
--- a/sky/tests/mutation-observer/shadow-dom.sky
+++ b/sky/tests/mutation-observer/shadow-dom.sky
@@ -7,7 +7,7 @@ describe('MutationObservers', function() {
   it('should handle shadow dom', function() {
     function mutate(element) {
       element.setAttribute('data-foo', 'bar');
-      element.insertBefore(document.createTextNode('hello'), element.firstChild);
+      element.insertBefore(new Text('hello'), element.firstChild);
       element.firstChild.textContent = 'goodbye';
       element.removeChild(element.firstChild);
     }