Add test case generator for runtime functions

R=dslomov@chromium.org, machenbach@chromium.org

Review URL: https://codereview.chromium.org/250923002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21199 ce2b1a6d-e550-0410-aec6-3dcde31c8c00