Add assertions to limit register count for VSTM and VLDM.
Add assertions to limit register count for VSTM and VLDM.

R=svenpanne@chromium.org
BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/10807066

git-svn-id: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@12166 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh