MIPS: Encapsulate the holder in the PropertyHolderCompilers.

Port r22704 (d3d7830)

BUG=
R=akos.palfi@imgtec.com

Review URL: https://codereview.chromium.org/427943003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22723 ce2b1a6d-e550-0410-aec6-3dcde31c8c00