Add some sweet XML classes.

client/html/src/DocumentFragment.dart

Index: client/html/src/DocumentFragment.dart
diff --git a/client/html/src/DocumentFragment.dart b/client/html/src/DocumentFragment.dart
index b58c6c07a4d3af575e2e890719d59320fe74d324..22bb3251b58177f39b004549692621c799949987 100644
--- a/client/html/src/DocumentFragment.dart
+++ b/client/html/src/DocumentFragment.dart
@@ -8,5 +8,9 @@ interface DocumentFragment extends Element default DocumentFragmentWrappingImple
 
   DocumentFragment.html(String html);
 
+  DocumentFragment.xml(String xml);

[Jacob, 2012/02/22 21:55:00]

should we include this method? we don't really want to encourage people to
heavily use XML.

[nweiz, 2012/02/23 00:35:06]

Because we allow all Element sub-interfaces to function as Elements, it's very
useful to have something like DocumentFragment that contains multiple elements
without a root. It makes some things much, much easier; see e.g. the
implementation of XMLElementWrappingImplementation#_insertAdjacentNode. We may
not want to encourage XML, but we don't want to make it painful either.

+
+  DocumentFragment.svg(String svg);
+
   DocumentFragment clone(bool deep);
 }