ARM: Make use of d16-d31 when available.

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 06b021669bd1792e150796f844f135935179dbdc..c5dbcf9bafe4c066522e537fafe7760937fd2acd 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -3033,8 +3033,8 @@ void LCodeGen::DoLoadKeyedExternalArray(LLoadKeyed* instr) {
         : Operand(key, LSL, shift_size);
     __ add(scratch0(), external_pointer, operand);
     if (elements_kind == EXTERNAL_FLOAT_ELEMENTS) {
-      __ vldr(result.low(), scratch0(), additional_offset);
-      __ vcvt_f64_f32(result, result.low());
+      __ vldr(DwVfpRegister::ScratchReg().low(), scratch0(), additional_offset);
+      __ vcvt_f64_f32(result, DwVfpRegister::ScratchReg().low());
     } else  {  // i.e. elements_kind == EXTERNAL_DOUBLE_ELEMENTS
       __ vldr(result, scratch0(), additional_offset);
     }
@@ -3704,7 +3704,7 @@ void LCodeGen::DoMathPowHalf(LUnaryMathOperation* instr) {
   __ b(&done, eq);
 
   // Add +0 to convert -0 to +0.
-  __ vadd(result, input, kDoubleRegZero);
+  __ vadd(result, input, DwVfpRegister::ZeroReg());
   __ vsqrt(result, result);
   __ bind(&done);
 }