Rename watch() and unwatch() to observe() and unobserve(), respectively, to avoid conflicts with Firefox's proprietary Object.prototype.watch method.
Rename validate() to validator(), and changed() to validate(), as the latter will be more frequently used, and better explains its purpose. Also, make the new validate() more concise.
see #21390.
git-svn-id: https://develop.svn.wordpress.org/trunk@21689 602fd350-edb4-49c9-b593-d223f7449a82
