Classes: Add test for method prototype

Methods should not have a prototype property

BUG=v8:3330
LOG=y
R=dslomov@chromium.org

Review URL: https://codereview.chromium.org/678103004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24939 ce2b1a6d-e550-0410-aec6-3dcde31c8c00