MIPS: thread isolate for HConstant::handle.

Port r16587 (45fc067)

BUG=

Review URL: https://codereview.chromium.org/23444041
Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@16596 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
put js accessor ics behind a flags until fixed

R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/23816009

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@16597 ce2b1a6d-e550-0410-aec6-3dcde31c8c00