- Replaced a few lines of codes in the parser by getNamedVariable
- Deleted unused commented out code in the parser

Change-Id: I34db0c971140a39cd91a32c05ebf866d5fca795b
Reviewed-on: https://swiftshader-review.googlesource.com/3670Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>