Update ICU to 5.2 (matching chromium)

BUG=v8:3452
R=svenpanne@chromium.org
LOG=y

Review URL: https://codereview.chromium.org/411493002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22523 ce2b1a6d-e550-0410-aec6-3dcde31c8c00