Add dummy dart:html library for documentation.

lib/html/doc/interface/BaseFontElement.dart

Index: lib/html/doc/interface/BaseFontElement.dart
diff --git a/lib/html/doc/interface/BaseFontElement.dart b/lib/html/doc/interface/BaseFontElement.dart
new file mode 100644
index 0000000000000000000000000000000000000000..5efb195eeb4271752a8a0af73bdf1b14ee749aa0
--- /dev/null
+++ b/lib/html/doc/interface/BaseFontElement.dart
@@ -0,0 +1,18 @@
+// Copyright (c) 2012, 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.
+
+// WARNING: Do not edit - generated code.
+
+/// @domName HTMLBaseFontElement
+interface BaseFontElement extends Element {
+
+  /** @domName HTMLBaseFontElement.color */
+  String color;
+
+  /** @domName HTMLBaseFontElement.face */
+  String face;
+
+  /** @domName HTMLBaseFontElement.size */
+  int size;
+}