MIPS: Call to the right slow method.

Port r14608 (339e0877)

BUG=

Review URL: https://codereview.chromium.org/14980008

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14627 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
MIPS: Track heap objects.

Port r14625 (bfb25ed8)

BUG=

Review URL: https://codereview.chromium.org/15102002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14628 ce2b1a6d-e550-0410-aec6-3dcde31c8c00