Prototype.js calls eval() on the response when the content type is set to...

Prototype.js calls eval() on the response when the content type is set to JavaScript, and eval() fails without the surrounding bracket.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@35344 71c3de6d-444a-0410-be80-ed276b4c234a