Get rid of SH_MAP_LONG_VARIABLE_NAMES.

We haven't been using it for a while, because if ANGLE detects we pass
in a hash function, it will turn on hashing and ignore
SH_MAP_LONG_VARIABLE_NAMES.

We already got rid of this option in ANGLE.  So in order to roll ANGLE,
we need to get rid of it in chromium.

BUG=
TEST=bots
R=bajones@chromium.org

Review URL: https://codereview.chromium.org/195463002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256298 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256298