Revert "Add support to load/store byte fields." and "MIPS: Add support to load/store byte fields.".

This reverts commit r17079 and r17085. Will reland after fix.

TBR=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/25679008

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17099 ce2b1a6d-e550-0410-aec6-3dcde31c8c00