Fix bug in HPhi::SimplifyConstantInput

R=jkummerow@chromium.org
BUG=269679

Review URL: https://codereview.chromium.org/23075003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@16174 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Use Cell instead of PropertyCell in DoCheckFunction (in case of new space object).

R=danno@chromium.org
BUG=

Review URL: https://codereview.chromium.org/23036004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@16175 ce2b1a6d-e550-0410-aec6-3dcde31c8c00