MIPS: Improve register allocation for Lithium representation changes on ARM

MIPS: Improve register allocation for Lithium representation changes on ARM

Port r10538 (21c5dc1).

MIPS-specific changes:
-moved MacroAssembler::SmiTagCheckOverflow definition to macro-assembler-mips.cc from the header
-added optimized 3-argument version of said function
-removed the related, completely unused TrySmiTag function

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/9296045
Patch from Daniel Kalmar <kalmard@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10567 ce2b1a6d-e550-0410-aec6-3dcde31c8c00