Add support for CSS unicod encoding to the text codec.

chrome/test/data/save_page/1.css

Index: chrome/test/data/save_page/1.css
diff --git a/chrome/test/data/save_page/1.css b/chrome/test/data/save_page/1.css
index 750524d60143ce218192923940d6d0c4d78201cd..d6c54980351cb251963e67264b2c9e84ab10b7c8 100644
--- a/chrome/test/data/save_page/1.css
+++ b/chrome/test/data/save_page/1.css
@@ -1,3 +1,13 @@
+/**
+ * Copyright 2015 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
 body {
   font-size: 20px;
-}
+}
+
+.icon:before {
+  content: "\e003 \e004 b";
+}
+