Adding Element.AddHTML and Element.addText methods.

lib/html/dart2js/html_dart2js.dart

Index: lib/html/dart2js/html_dart2js.dart
diff --git a/lib/html/dart2js/html_dart2js.dart b/lib/html/dart2js/html_dart2js.dart
index 8dea02e5bc2ef041a587e7f8ecb16ca6676b336b..ecb288b5a64f2de95906ba243feda4d91f868735 100644
--- a/lib/html/dart2js/html_dart2js.dart
+++ b/lib/html/dart2js/html_dart2js.dart
@@ -5146,6 +5146,14 @@ class _DocumentFragmentImpl extends _NodeImpl implements DocumentFragment native
     this._insertAdjacentNode(where, new DocumentFragment.html(text));
   }
 
+  void addText(String text) {
+    this.insertAdjacentText('beforeend', text);
+  }
+
+  void addHTML(String text) {
+    this.insertAdjacentHTML('beforeend', text);
+  }
+
   Future<ElementRect> get rect() {
     return _createMeasurementFuture(() => const EmptyElementRect(),
                                     new Completer<ElementRect>());
@@ -5963,14 +5971,14 @@ class _ElementRectImpl implements ElementRect {
 
   // TODO(jacobr): should we move these outside of ElementRect to avoid the
   // overhead of computing them every time even though they are rarely used.
-  final _ClientRectImpl _boundingClientRect; 
+  final _ClientRectImpl _boundingClientRect;
   final _ClientRectListImpl _clientRects;
 
   _ElementRectImpl(_ElementImpl element) :
     client = new _SimpleClientRect(element.$dom_clientLeft,
                                   element.$dom_clientTop,
-                                  element.$dom_clientWidth, 
-                                  element.$dom_clientHeight), 
+                                  element.$dom_clientWidth,
+                                  element.$dom_clientHeight),
     offset = new _SimpleClientRect(element.$dom_offsetLeft,
                                   element.$dom_offsetTop,
                                   element.$dom_offsetWidth,
@@ -6059,6 +6067,14 @@ class _ElementImpl extends _NodeImpl implements Element native "*Element" {
         new Completer<CSSStyleDeclaration>());
   }
 
+  void addText(String text) {
+    this.insertAdjacentText('beforeend', text);
+  }
+
+  void addHTML(String text) {
+    this.insertAdjacentHTML('beforeend', text);
+  }
+
   // Hooks to support custom WebComponents.
   var xtag;
 
@@ -23225,6 +23241,9 @@ interface Element extends Node, NodeSelector default _ElementFactoryProvider {
   AttributeMap get dataAttributes();
   void set dataAttributes(Map<String, String> value);
 
+  void addText(String text);
+  void addHTML(String html);
+
   /**
    * @domName getClientRects, getBoundingClientRect, clientHeight, clientWidth,
    * clientTop, clientLeft, offsetHeight, offsetWidth, offsetTop, offsetLeft,