Add back ascii fast path for toupper/tolower

R=yangguo@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/11889007
Patch from Dan Carney <dcarney@google.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13376 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Prepare push to trunk.  Now working on version 3.16.6.

R=ulan@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/11885038

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13377 ce2b1a6d-e550-0410-aec6-3dcde31c8c00