This is not really anything new. Most code already followed these
sniffs. This patch just fixes the remaining exceptions. Also:
* Remove PHPDoc blocks that don't add anything but just repeat the
strict types.
* Remove @file comments in favor of class-level comments.
* Add strict types where possible, most notably some `void`.
Change-Id: Iff6872dff68170b0fc4e82ac2ba3cad385e8773e
