Add html4-defs.js, html-sanitizer.js from google caja project.

 * http://google-caja.googlecode.com
  - /svn-history/r2466/trunk/src/com/google/caja/plugin/html4-defs.js
  - /svn-history/r5661/trunk/src/com/google/caja/plugin/html-sanitizer.js

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>