Revert "ARM: Improve register allocation and constraints."

Revert "ARM: Improve register allocation and constraints."

This reverts r8381.

It was causing Mozilla test mozilla/ecma/Date/15.9.3.8-5 to fail and Sputnik tests S15.9.3.1_A5_T5, S15.9.3.1_A5_T1, S15.9.3.1_A5_T2, S15.9.3.1_A5_T4, S15.9.3.1_A5_T3 and S15.9.3.1_A5_T6 to timeout.

R=ager@chromium.org

BUG=none
TEST=mozilla/ecma/Date/15.9.3.8-5, S15.9.3.1_A5_T5, S15.9.3.1_A5_T1, S15.9.3.1_A5_T2, S15.9.3.1_A5_T4, S15.9.3.1_A5_T3 and S15.9.3.1_A5_T6

Review URL: http://codereview.chromium.org//7246004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8397 ce2b1a6d-e550-0410-aec6-3dcde31c8c00