Refactor RangeBoundary +/- infinity to be distinct RangeBoundary kinds.

runtime/vm/intermediate_language_arm64.cc

Index: runtime/vm/intermediate_language_arm64.cc
diff --git a/runtime/vm/intermediate_language_arm64.cc b/runtime/vm/intermediate_language_arm64.cc
index ec073f7f5f641528cee0a856f01c76a9ed6b365e..c39381254b017033e863d5a6959a0c8745b30f3e 100644
--- a/runtime/vm/intermediate_language_arm64.cc
+++ b/runtime/vm/intermediate_language_arm64.cc
@@ -2578,8 +2578,7 @@ static void EmitSmiShiftLeft(FlowGraphCompiler* compiler,
   if (is_truncating) {
     if (right_needs_check) {
       const bool right_may_be_negative =
-          (right_range == NULL) ||
-          !right_range->IsWithin(0, RangeBoundary::kPlusInfinity);
+          (right_range == NULL) || right_range->IsNegative();
       if (right_may_be_negative) {
         ASSERT(shift_left->CanDeoptimize());
         __ CompareRegisters(right, ZR);
@@ -2912,7 +2911,7 @@ void BinarySmiOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
       // sarl operation masks the count to 6 bits.
       const intptr_t kCountLimit = 0x3F;
       if ((right_range == NULL) ||
-          !right_range->IsWithin(RangeBoundary::kMinusInfinity, kCountLimit)) {
+          !right_range->OnlyLessThanOrEqualTo(kCountLimit)) {
         __ LoadImmediate(TMP2, kCountLimit, PP);
         __ CompareRegisters(TMP, TMP2);
         __ csel(TMP, TMP2, TMP, GT);