Convert ElementsKind into a BitField

src/arm64/macro-assembler-arm64.cc

Index: src/arm64/macro-assembler-arm64.cc
diff --git a/src/arm64/macro-assembler-arm64.cc b/src/arm64/macro-assembler-arm64.cc
index 75fd2b62be2641cfcc875f9c068c3d7d691b7758..1e960514fa62f04c05172c9614cb8e68c5e1fcb9 100644
--- a/src/arm64/macro-assembler-arm64.cc
+++ b/src/arm64/macro-assembler-arm64.cc
@@ -3764,7 +3764,7 @@ void MacroAssembler::LoadElementsKindFromMap(Register result, Register map) {
   // Load the map's "bit field 2".
   __ Ldrb(result, FieldMemOperand(map, Map::kBitField2Offset));
   // Retrieve elements_kind from bit field 2.
-  __ Ubfx(result, result, Map::kElementsKindShift, Map::kElementsKindBitCount);
+  DecodeField<Map::ElementsKindBits>(result);
 }
 
 
@@ -4539,7 +4539,7 @@ void MacroAssembler::JumpIfDictionaryInPrototypeChain(
   Bind(&loop_again);
   Ldr(current, FieldMemOperand(current, HeapObject::kMapOffset));
   Ldrb(scratch1, FieldMemOperand(current, Map::kBitField2Offset));
-  Ubfx(scratch1, scratch1, Map::kElementsKindShift, Map::kElementsKindBitCount);
+  DecodeField<Map::ElementsKindBits>(scratch1);
   CompareAndBranch(scratch1, DICTIONARY_ELEMENTS, eq, found);
   Ldr(current, FieldMemOperand(current, Map::kPrototypeOffset));
   CompareAndBranch(current, Operand(factory->null_value()), ne, &loop_again);