The hhvm redis client returns false instead of null. This caused
JobQueueRedis to get stuck in an infinite loop. This works around the
difference by catching null as a signal for no more jobs.
It can be reverted when https://github.com/facebook/hhvm/pull/3127/ is
in all versions of hhvm we expect to run MediaWiki.
Bug: 67622
Change-Id: I9bbad42f36a80635097b8e0140b48b6492b2f0f5
Swapped some "$var type" to "type $var" or added missing types
before the $var. Changed some other types to match the more common
spelling. Makes beginning of some text in captial.
Change-Id: Ifbb1da2a6278b0bde2a6f6ce2e7bd383ee3fb28a
