Fix DoDeferredNumberTagU to keep the value in xmm1 instead of xmm0 on x64.

Fix DoDeferredNumberTagU to keep the value in xmm1 instead of xmm0 on x64.

xmm0 is not saved across runtime call on x64 because MacroAssembler::EnterExitFrameEpilogue preserves only allocatable XMM registers unlike on ia32 where it preserves all registers.

Cleanup handling of shifts: SHR can deoptimize only when its a shift by 0, all other shift never deoptimize.

Fix type inference for i-to-t change instruction. On X64 this ensures that write-barrier is generated correctly.

R=danno@chromium.org

Review URL: https://chromiumcodereview.appspot.com/10868032

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12373 ce2b1a6d-e550-0410-aec6-3dcde31c8c00