Use PHP type hinting in `ArcanistXHPASTLinter`.
Use PHP type hinting in `ArcanistXHPASTLinter`.

Summary: Explicitly specify the types of the function parameters. This change is basically the same as D8388.

Test Plan: `arc unit`.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9040

Symplicity/arcanist,fivestars/arcanist,codelabs-ch/arcanist,sneakpeeq/arcanist,kevinseelbach/arcanist,memsql/arcanist,dguo-coursera/arcanist,phacility/arcanist,codelabs-ch/arcanist,calblueprint/arcanist,dguo-coursera/arcanist,KieranHayes/arcanist,Symplicity/arcanist,phacility/arcanist,eSpark/arcanist,r4nt/arcanist,eSpark/arcanist,uber/arcanist,KieranHayes/arcanist,alexmv/arcanist,wikimedia/phabricator-arcanist,phacility/arcanist,aik099/arcanist,zhihu/arcanist,Symplicity/arcanist,r4nt/arcanist,uber/arcanist,phacility/arcanist,codelabs-ch/arcanist,wxstars/arcanist,coursera/arcanist,coursera/arcanist,Khan/arcanist,hach-que/arcanist,jra3/arcanist,dguo-coursera/arcanist,wikimedia/phabricator-arcanist,eSpark/arcanist,hach-que/arcanist,dguo-coursera/arcanist,uber/arcanist,wxstars/arcanist,haskell-infra/arcanist,memsql/arcanist,wharris/arcanist,kevinseelbach/arcanist,folsom-labs/arcanist,calblueprint/arcanist,coursera/arcanist,folsom-labs/arcanist,chundongwang/arcanist,alexmv/arcanist,zhihu/arcanist,KieranHayes/arcanist,haskell-infra/arcanist,codelabs-ch/arcanist,sneakpeeq/arcanist,alexmv/arcanist,sneakpeeq/arcanist,KieranHayes/arcanist,chundongwang/arcanist,folsom-labs/arcanist,PageUpPeopleOrg/arcanist-patches,calblueprint/arcanist,zhihu/arcanist,calblueprint/arcanist,aik099/arcanist,Symplicity/arcanist,haskell-infra/arcanist,r4nt/arcanist,wikimedia/phabricator-arcanist,r4nt/arcanist,hach-que/arcanist,memsql/arcanist,fivestars/arcanist,fivestars/arcanist,haskell-infra/arcanist,Khan/arcanist,sneakpeeq/arcanist,kevinseelbach/arcanist,chundongwang/arcanist,kevinseelbach/arcanist,phacility/arcanist,codelabs-ch/arcanist,PageUpPeopleOrg/arcanist-patches,wharris/arcanist,coursera/arcanist,wikimedia/phabricator-arcanist,wharris/arcanist,wharris/arcanist,wxstars/arcanist,Khan/arcanist,wxstars/arcanist,folsom-labs/arcanist,jra3/arcanist,zhihu/arcanist,jra3/arcanist,PageUpPeopleOrg/arcanist-patches,aik099/arcanist,aik099/arcanist,PageUpPeopleOrg/arcanist-patches,fivestars/arcanist,chundongwang/arcanist,memsql/arcanist,Khan/arcanist,alexmv/arcanist,hach-que/arcanist,uber/arcanist,eSpark/arcanist,jra3/arcanist