MIPS: Improved function entry hook coverage.

Port r15384 (d553efd)

Original commit message:
Adds more coverage for function entry hook, sufficient to capture profiles
that are contiguous from C++, through JS and back out to C++.

BUG=

Review URL: https://codereview.chromium.org/18184011
Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15396 ce2b1a6d-e550-0410-aec6-3dcde31c8c00