Introduce SmiValuesAre31Bits and SmiValuesAre32Bits global predicate functions

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index 9c9b1620e586ce5872bbc46de2eaf515266716a0..76e0d6b37bd88ef9788e8f1e2e34b4f29c082ae8 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -992,7 +992,7 @@ bool MacroAssembler::IsUnsafeInt(const int x) {
 
 void MacroAssembler::SafeMove(Register dst, Smi* src) {
   ASSERT(!dst.is(kScratchRegister));
-  ASSERT(kSmiValueSize == 32);  // JIT cookie can be converted to Smi.
+  ASSERT(SmiValuesAre32Bits());  // JIT cookie can be converted to Smi.
   if (IsUnsafeInt(src->value()) && jit_cookie() != 0) {
     Move(dst, Smi::FromInt(src->value() ^ jit_cookie()));
     Move(kScratchRegister, Smi::FromInt(jit_cookie()));
@@ -1004,7 +1004,7 @@ void MacroAssembler::SafeMove(Register dst, Smi* src) {
 
 
 void MacroAssembler::SafePush(Smi* src) {
-  ASSERT(kSmiValueSize == 32);  // JIT cookie can be converted to Smi.
+  ASSERT(SmiValuesAre32Bits());  // JIT cookie can be converted to Smi.
   if (IsUnsafeInt(src->value()) && jit_cookie() != 0) {
     Push(Smi::FromInt(src->value() ^ jit_cookie()));
     Move(kScratchRegister, Smi::FromInt(jit_cookie()));