Replace createTextNode with new Text().

sky/tests/mutation-observer/observe-characterdata.sky

Index: sky/tests/mutation-observer/observe-characterdata.sky
diff --git a/sky/tests/mutation-observer/observe-characterdata.sky b/sky/tests/mutation-observer/observe-characterdata.sky
index 21f2de6cea3901aff412c67b30e3fb208440c6a1..df264d94bce20c6608def5834704672cdda27e71 100644
--- a/sky/tests/mutation-observer/observe-characterdata.sky
+++ b/sky/tests/mutation-observer/observe-characterdata.sky
@@ -41,7 +41,7 @@ describe('MutationObserver on character data', function() {
             // ...observer.disconnect() should prevent further delivery of mutations.
 
             assert.equal(mutations, null);
-            charDataNode = document.createTextNode('');
+            charDataNode = new Text('');
             observer.observe(charDataNode, { characterData: true });
             charDataNode.textContent = 'foo';
             charDataNode.textContent = 'bar';