Remove several dead assignments from HarfBuzzShaper.cpp

Remove dead assignments from HarfBuzzShaper.cpp that the clang static code
analyzer was complaining about. Those variables were being assigned but
never read after.

R=eae@chromium.org, tonyg@chromium.org

Review URL: https://codereview.chromium.org/243293005

git-svn-id: svn://svn.chromium.org/blink/trunk@172039 bbb929c8-8fbe-4397-9dbb-9b2b20218538