Introduce SmiValuesAre31Bits and SmiValuesAre32Bits global predicate functions

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index f977a750d946a6b24d657b08229fc4a238c368b2..f7166a900d72e0456fae40db9204e5bb1fe91cf9 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -3267,7 +3267,7 @@ class HConstant: public HTemplateInstruction<0> {
   }
 
   virtual Representation KnownOptimalRepresentation() {
-    if (HasSmiValue() && kSmiValueSize == 31) return Representation::Smi();
+    if (HasSmiValue() && SmiValuesAre31Bits()) return Representation::Smi();
     if (HasInteger32Value()) return Representation::Integer32();
     if (HasNumberValue()) return Representation::Double();
     if (HasExternalReferenceValue()) return Representation::External();
@@ -5696,7 +5696,7 @@ class ArrayInstructionInterface {
   virtual ~ArrayInstructionInterface() { };
 
   static Representation KeyedAccessIndexRequirement(Representation r) {
-    return r.IsInteger32() || kSmiValueSize != 31
+    return r.IsInteger32() || SmiValuesAre32Bits()
         ? Representation::Integer32() : Representation::Smi();
   }
 };