fix the simulator behaviour.

BUG=none
TEST=added to cctest/test-assembler-arm.cc

Patch by Rodolph Perfetta from ARM Ltd.

Review URL: http://codereview.chromium.org/6368053


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6629 ce2b1a6d-e550-0410-aec6-3dcde31c8c00