Move __Const checks from nast check to parsing
Summary:
- Non const classes can extend __Const classes
- Moved disallow abstract final class check to parsing
- Removed redundant 'disallow __Const on traits, interfaces, and enums' check from nast check
- The case Crecord in NastCheck currently has no error-checking during parsing. It also currently will never parse a __ Const attribute as 'missing' is passed in along every parsing path for parse_record_declaration. I made a post on Hacklang Engineering to see if the plan is to further deprecate these or whether we need to add any checks on them.
Reviewed By: alexeyt
Differential Revision:
D16522670
fbshipit-source-id:
26ffa1cce177bb2e6a719ffcf4132afa52eb7342