[crankshaft] Refactor kAllowUndefinedAsNaN to kTruncatingToNumber.

src/crankshaft/arm64/lithium-codegen-arm64.cc

Index: src/crankshaft/arm64/lithium-codegen-arm64.cc
diff --git a/src/crankshaft/arm64/lithium-codegen-arm64.cc b/src/crankshaft/arm64/lithium-codegen-arm64.cc
index b07dc256f50446611b1f41c4836f7a3a49528d2b..d2c024f79d2790a9201780ea157f98bb3e37a1bf 100644
--- a/src/crankshaft/arm64/lithium-codegen-arm64.cc
+++ b/src/crankshaft/arm64/lithium-codegen-arm64.cc
@@ -4204,8 +4204,7 @@ void LCodeGen::DoNumberUntagD(LNumberUntagD* instr) {
   Register input = ToRegister(instr->value());
   Register scratch = ToRegister(instr->temp());
   DoubleRegister result = ToDoubleRegister(instr->result());
-  bool can_convert_undefined_to_nan =
-      instr->hydrogen()->can_convert_undefined_to_nan();
+  bool can_convert_undefined_to_nan = instr->truncating();
 
   Label done, load_smi;