To distinguish the tokens we used to track the lexer context,
which is fragile. This patch implements a better way -
combine the two tokens into a common parser rule and let
the parser context decide if the declaration is valid,
which it already does by checking the naming conflicts.

TRAC #23158

Signed-off-by: Nicolas Capens
Merged-by: Jamie Madill
Authored-by: alokp@chromium.org

git-svn-url: https://code.google.com/p/angleproject/source/detail?r=2190
Review URL: https://codereview.appspot.com/8797044