Fix two CPU profiler tests on ARM and MIPS simulators

Use Simulator::get_pc instead of Simulator::get_register(pc) as the latter
will return value adjusted by Instruction::kPCReadOffset.

BUG=v8:2628
R=loislo@chromium.org, svenpanne@chromium.org

Review URL: https://codereview.chromium.org/16154004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14880 ce2b1a6d-e550-0410-aec6-3dcde31c8c00