Googlebot Running Javascript

One important information is missing here: the IP address of the crawler, the official Googlebot can then be identified. There are so many bots out there disguised as Googlebots, most of them do weird things: scanning for log-in pages, sending POST requests with spam, searching for vulnerable sites.

The Googlebot has been seen using POST requests and executing JavaScript for some time now. There is even an official article on this topic on the Google Webmaster Central blog:

http://googlewebmastercentral.blogspot.com/2011/11/get-post-... (from Nov. 2011)