Fix y-umlaut to uppercase.

R=dcarney@chromium.org
BUG=v8:2984

Review URL: https://codereview.chromium.org/59853006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17545 ce2b1a6d-e550-0410-aec6-3dcde31c8c00