Changes to make it easier to add elements.

sdk/lib/html/templates/html/impl/impl_DocumentFragment.darttemplate

Index: sdk/lib/html/templates/html/impl/impl_DocumentFragment.darttemplate
diff --git a/sdk/lib/html/templates/html/impl/impl_DocumentFragment.darttemplate b/sdk/lib/html/templates/html/impl/impl_DocumentFragment.darttemplate
index 2106a73f8b0a9ae25924209257491fe6c976dd2a..3ad35f019512b9e3cfed0f1d59e56e95cd1ce415 100644
--- a/sdk/lib/html/templates/html/impl/impl_DocumentFragment.darttemplate
+++ b/sdk/lib/html/templates/html/impl/impl_DocumentFragment.darttemplate
@@ -110,11 +110,15 @@ $endif
     this._insertAdjacentNode(where, new DocumentFragment.html(text));
   }
 
-  void addText(String text) {
+  void append(Element element) {
+    this.children.add(element);
+  }
+
+  void appendText(String text) {
     this.insertAdjacentText('beforeend', text);
   }
 
-  void addHtml(String text) {
+  void appendHtml(String text) {
     this.insertAdjacentHTML('beforeend', text);
   }