Changes to make it easier to add elements.

sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index fb5f63a09b54670174a2d34eb79ffb8d71c9dae4..d039ca665cd32cde5b46fdc9e00332d57fd28927 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -8854,11 +8854,15 @@ class DocumentFragment extends Node {
     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);
   }
 
@@ -9708,9 +9712,16 @@ abstract class Element extends Node implements ElementTraversal {
   }
 
   /**
+   * 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);
   }
 
@@ -9718,7 +9729,7 @@ abstract class Element extends Node implements ElementTraversal {
    * 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);
   }