Partial revert of Idc3d42be7

This patch reverts a change that I piggybacked on Idc3d42be7 without intending
to -- specifically replacing JsonSchemaHooks::registerHandlers with an
anonymous function in EventLogging.php.

This partially reverts commit 068fffb965d857f7f93f911876b6b3d0e3852b13.

Change-Id: I09ebc5abf062c1d74348a6ec199f90bb35769968