Add some sweet XML classes.

client/html/src/DocumentFragmentWrappingImplementation.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class FilteredElementList implements ElementList {
   final Node _node;
   final NodeList _childNodes;
 
   FilteredElementList(Node node): _childNodes = node.nodes, _node = node;
 
@@ skipping 146 matching lines @@
     return new DocumentFragmentWrappingImplementation._wrap(
             dom.document.createDocumentFragment());
   }
 
   factory DocumentFragmentWrappingImplementation.html(String html) {
     var fragment = new DocumentFragment();
     fragment.innerHTML = html;
     return fragment;
   }
 
+  factory DocumentFragmentWrappingImplementation.xml(String xml) {
+    var fragment = new DocumentFragment();
+    var e = new XMLElement.tag("xml");
+    e.innerHTML = xml;
+
+    // Copy list first since we don't want liveness during iteration.
+    List nodes = new List.from(e.nodes);
+    fragment.nodes.addAll(nodes);
+    return fragment;
+  }
+
+  factory DocumentFragmentWrappingImplementation.svg(String svg) {
+    var fragment = new DocumentFragment();
+    var e = new SVGSVGElement();
+    e.innerHTML = svg;
+
+    // Copy list first since we don't want liveness during iteration.
+    List nodes = new List.from(e.nodes);
+    fragment.nodes.addAll(nodes);
+    return fragment;
+  }
+
   ElementList get elements() {
     if (_elements == null) {
       _elements = new FilteredElementList(this);
     }
     return _elements;
   }
 
   // TODO: The type of value should be Collection<Element>. See http://b/5392897
   void set elements(value) {
     // Copy list first since we don't want liveness during iteration.
     List copy = new List.from(value);
     final elements = this.elements;
     elements.clear();
     elements.addAll(copy);
   }
 
   String get innerHTML() {
     var e = new Element.tag("div");
     e.nodes.add(this.clone(true));
     return e.innerHTML;
   }
 
   String get outerHTML() => innerHTML;
 
+  // TODO(nweiz): Do we want to support some variant of innerHTML for XML and/or
+  // SVG strings?
   void set innerHTML(String value) {
     this.nodes.clear();
 
     var e = new Element.tag("div");
     e.innerHTML = value;
 
     // Copy list first since we don't want liveness during iteration.
     List nodes = new List.from(e.nodes);
     this.nodes.addAll(nodes);
   }
@@ skipping 164 matching lines @@
       "Title can't be set for document fragments.");
   }
 
   void set webkitdropzone(String value) {
     throw new UnsupportedOperationException(
       "WebKit drop zone can't be set for document fragments.");
   }
 
   DocumentFragment clone(bool deep) => super.clone(deep);
 }