The method for getting the declaring class name was not used when
printing the class name, and was incorrect anyway. Use reflection
when on the error path to ensure the correct class name is used.
Change-Id: Ic9cd4319535d5ab877a0563e0433371e1025d985
self::class would have been better here for consistency across
the code base but seems HHVM handles self::class diferrently from
PHP 7, when used inside a trait. The difference is significant to the
tests and thus we keep the result the same by using __CLASS__ instead.
Change-Id: I58b452341a0567f4d6e6636a7e489531a5569d20
