Make DocumentFragment implement Element.

client/html/src/ElementWrappingImplementation.dart

Index: client/html/src/ElementWrappingImplementation.dart
diff --git a/client/html/src/ElementWrappingImplementation.dart b/client/html/src/ElementWrappingImplementation.dart
index d1775766d2645c95e4376c5e706c3ed4980a2703..455b5818e58650d80706ea2dc15c37cb48d9dd8d 100644
--- a/client/html/src/ElementWrappingImplementation.dart
+++ b/client/html/src/ElementWrappingImplementation.dart
@@ -602,8 +602,13 @@ class ElementWrappingImplementation extends NodeWrappingImplementation implement
     return LevelDom.wrapClientRect(_ptr.getBoundingClientRect());
   }
 
-  ClientRectList getClientRects() {
-    return LevelDom.wrapClientRectList(_ptr.getClientRects());
+  List<ClientRect> getClientRects() {
+    var rects = LevelDom.wrapClientRectList(_ptr.getClientRects());
+    var out = new List(rects.length);
+    for (var i = 0; i < rects.length; i++) {
+      out.add(rects.item(i));
+    }
+    return out;
   }
 
   Element insertAdjacentElement([String where = null, Element element = null]) {