Identifier is sufficient to parse struct fieldname.

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=2195
Review URL: https://codereview.appspot.com/8709048