PPC/s390: [crankshaft] Refactor kAllowUndefinedAsNaN to kTruncatingToNumber.

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

Index: src/crankshaft/ppc/lithium-codegen-ppc.cc
diff --git a/src/crankshaft/ppc/lithium-codegen-ppc.cc b/src/crankshaft/ppc/lithium-codegen-ppc.cc
index 26b04c6512b750e0516ab380db2d941cd4448162..c7f0a38694908c07889f98dfdd1cc197a0afacae 100644
--- a/src/crankshaft/ppc/lithium-codegen-ppc.cc
+++ b/src/crankshaft/ppc/lithium-codegen-ppc.cc
@@ -4725,8 +4725,7 @@ void LCodeGen::DoSmiUntag(LSmiUntag* instr) {
 void LCodeGen::EmitNumberUntagD(LNumberUntagD* instr, Register input_reg,
                                 DoubleRegister result_reg,
                                 NumberUntagDMode mode) {
-  bool can_convert_undefined_to_nan =
-      instr->hydrogen()->can_convert_undefined_to_nan();
+  bool can_convert_undefined_to_nan = instr->truncating();
   bool deoptimize_on_minus_zero = instr->hydrogen()->deoptimize_on_minus_zero();
 
   Register scratch = scratch0();