MIPS: Refactor PropertyCallbackInfo & FunctionCallbackInfo, part 3.

Port r17032 (3bdce1d)

Original commit message:
This CL starts using positive array indices instead of negative array indices
for the PropertyCallbackInfo and FunctionCallbackInfo fields. Also, the indices
match now, so they can be unified in the next step.

BUG=
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/25549002

Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17056 ce2b1a6d-e550-0410-aec6-3dcde31c8c00