Shorten autogenerated error message for functions only.

R=yangguo@chromium.org, Yang, rossberg@chromium.org
BUG=v8:3019, chromium:331971
LOG=Y

Review URL: https://codereview.chromium.org/271733005

Patch from Andrey Adaykin <aandrey@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21224 ce2b1a6d-e550-0410-aec6-3dcde31c8c00