MIPS: Prefill pre-allocated memory of folded allocation with one pointer fillers when heap verifier is on.

Port r15798 (3b92806)

BUG=

Review URL: https://codereview.chromium.org/19485006
Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15809 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Add test case for issue 2793 about experimental natives.

R=yangguo@chromium.org
BUG=v8:2793

Review URL: https://codereview.chromium.org/19948002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15810 ce2b1a6d-e550-0410-aec6-3dcde31c8c00