Changes to make it easier to add elements.

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 027cd6785c516c37ea2c73e42908fac87ae1ecfe..2421183bb89b1f126bed6b6f029c5431e73f437b 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -6869,11 +6869,15 @@ class DocumentFragment extends Node native "*DocumentFragment" {
     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);
   }
 
@@ -7695,9 +7699,16 @@ abstract class Element extends Node implements ElementTraversal native "*Element
   }
 
   /**
+   * Adds the specified element to after the last child of this.
+   */
+  void append(Element e) {
+    this.children.add(e);
+  }
+
+  /**
    * Adds the specified text as a text node after the last child of this.
    */
-  void addText(String text) {
+  void appendText(String text) {
     this.insertAdjacentText('beforeend', text);
   }
 
@@ -7705,7 +7716,7 @@ abstract class Element extends Node implements ElementTraversal native "*Element
    * Parses the specified text as HTML and adds the resulting node after the
    * last child of this.
    */
-  void addHtml(String text) {
+  void appendHtml(String text) {
     this.insertAdjacentHTML('beforeend', text);
   }