Fix for bug 81753, do not read past the end of unicode strings

BUG=81753
TEST=unit_tests


Review URL: http://codereview.chromium.org/7891051

git-svn-id: http://src.chromium.org/svn/trunk/deps/third_party/icu46@101167 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
3 files changed