MIPS: Clean up handling of global cell stores in the optimizing compiler.

MIPS: Clean up handling of global cell stores in the optimizing compiler.

Port r10280 (5f6aec5).

Original commit message:

Tell the register allocator the value is not overwritten.  Never use
temporary registers on ia32, avoid them on x64 and ARM.  Restore the
original copyright date on assembler.cc.

BUG=
TEST=

Review URL: http://codereview.chromium.org/9004017
Patch from Daniel Kalmar <kalmard@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10281 ce2b1a6d-e550-0410-aec6-3dcde31c8c00