Restore adoptNode and importNode to dart:html

tests/html/document_test.dart

Index: tests/html/document_test.dart
diff --git a/tests/html/document_test.dart b/tests/html/document_test.dart
index fece53edeb88ec190262a1557e2db16633a76591..ca04a0f96cedfd40362635985385535ef2a81d74 100644
--- a/tests/html/document_test.dart
+++ b/tests/html/document_test.dart
@@ -61,5 +61,24 @@ main() {
       expect(new Element.tag('a'), isAnchorElement);
       expect(new Element.tag('bad_name'), isUnknownElement);
     });
+
+    test('adoptNode', () {
+      var div = new Element.html('<div><div id="foo">bar</div></div>');
+      var doc = document.implementation.createHtmlDocument('');
+      expect(doc.adoptNode(div), div);
+      expect(div.document, doc);
+      doc.body.nodes.add(div);
+      expect(doc.query('#foo').text, 'bar');
+    });
+
+    test('importNode', () {
+      var div = new Element.html('<div><div id="foo">bar</div></div>');
+      var doc = document.implementation.createHtmlDocument('');
+      var div2 = doc.importNode(div, true);
+      expect(div2, isNot(equals(div)));
+      expect(div2.document, doc);
+      doc.body.nodes.add(div2);
+      expect(doc.query('#foo').text, 'bar');
+    });
   });
 }