Remove makegrammar.pl

This Perl script no longer has any purpose. All it does is concatenate two
files. We might as well just check in the concatenated file.

R=jchaffraix@chromium.org

Review URL: https://codereview.chromium.org/41483002

git-svn-id: svn://svn.chromium.org/blink/trunk@160501 bbb929c8-8fbe-4397-9dbb-9b2b20218538