Optimize mov sequence when applicable.

Conflicts:

	src/ppc/assembler-ppc.cc
	src/ppc/deoptimizer-ppc.cc
Clean up CODE_STUB_LIST_PPC.
Fix write barrier input in KeyedStoreIC::GenerateNonStrictArguments.
PPC: Simplify code aging.

Conflicts:

	src/ppc/codegen-ppc.cc
	src/ppc/macro-assembler-ppc.cc