Only use the non-strict-arguments-stub if the store site is non-strict.

BUG=349874
LOG=N
R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/176843018

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19690 ce2b1a6d-e550-0410-aec6-3dcde31c8c00