Introduce SmiValuesAre31Bits and SmiValuesAre32Bits global predicate functions

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 24ee60f1bb4dcec1934b5d1a486f41bc734dd2f0..385b329c3522dffab4b77baf35aca7b38248556c 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -5452,6 +5452,8 @@ template <> struct SmiTagging<8> {
 typedef SmiTagging<kApiPointerSize> PlatformSmiTagging;
 const int kSmiShiftSize = PlatformSmiTagging::kSmiShiftSize;
 const int kSmiValueSize = PlatformSmiTagging::kSmiValueSize;
+V8_INLINE(static bool SmiValuesAre31Bits()) { return kSmiValueSize == 31; }
+V8_INLINE(static bool SmiValuesAre32Bits()) { return kSmiValueSize == 32; }
 
 /**
  * This class exports constants and functionality from within v8 that