Fix case insensitivity of PHP keywords
Summary:
This changes all PHP keywords + a few Hack ones to be case insensitive.
Words like "dynamic" and "mixed" which are only valid keywords in PHP will mostly stay case sensitive(I changed a few of them anyway before I decided it was too annoying), but PHP builtins will be case insensitive after this diff.
Fixes https://github.com/facebook/hhvm/issues/8194
Reviewed By: oulgen, alexeyt
Differential Revision:
D7958203
fbshipit-source-id:
cdd83616d2fb2ab1c5340cf8171aba3085f3bfe8