Continue to register them, pulling from ajax.googleapis.com. This is only being done for backwards compatibility;
libraries in use will continue to be local sources.
In the process, update to the latest versions of Prototype (1.7.1, June 5) and script.aculo.us (1.9.0, from 2010).
props helenyhou.
fixes#21661, #16664, #16665.
git-svn-id: https://develop.svn.wordpress.org/trunk@21593 602fd350-edb4-49c9-b593-d223f7449a82
64caad03e7