Increase the number of allocations in OptimizedPretenuringdoubleArrayLiterals test to make sure that pretenuring decisions are not flaky on the tests bots.

BUG=

Review URL: https://codereview.chromium.org/129783006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18746 ce2b1a6d-e550-0410-aec6-3dcde31c8c00