More crankshaft fixes

- Convert: MacroAssembler::StoreToSafepointRegistersAndDoublesSlot
           MacroAssembler::StoreToSafepointRegisterSlot
           MacroAssembler::LoadFromSafepointRegisterSlot
           LCodeGen::DoMathMinMax
           LCodeGen::DoCmpIDAndBranch
           LCodeGen::DoHasInstanceTypeAndBranch(
           LCodeGen::DoBranch (most cases)

- Provide Assembler::fsel and Assembler::fneg (floating point select
  and negate operations).