Only jump over 'else' part of a conditional if it is actually
generated.  Update a comment to more correctly reflect what is going
on.

Review URL: http://codereview.chromium.org/155272

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2402 ce2b1a6d-e550-0410-aec6-3dcde31c8c00