Address review comments for r39595.

runtime/vm/intermediate_language_mips.cc

Index: runtime/vm/intermediate_language_mips.cc
diff --git a/runtime/vm/intermediate_language_mips.cc b/runtime/vm/intermediate_language_mips.cc
index 645f87b9036eda7db9230c576ee9d5e09a26578e..4505997b77b389138cd6dea752845c1ac6f7cfa9 100644
--- a/runtime/vm/intermediate_language_mips.cc
+++ b/runtime/vm/intermediate_language_mips.cc
@@ -2655,8 +2655,7 @@ static void EmitSmiShiftLeft(FlowGraphCompiler* compiler,
       }
       const intptr_t max_right = kSmiBits - Utils::HighestBit(left_int);
       const bool right_needs_check =
-          (right_range == NULL) ||
-          !right_range->IsWithin(0, max_right - 1);
+          !RangeUtils::IsWithin(right_range, 0, max_right - 1);
       if (right_needs_check) {
         __ BranchUnsignedGreaterEqual(
             right, reinterpret_cast<int32_t>(Smi::New(max_right)), deopt);
@@ -2668,7 +2667,7 @@ static void EmitSmiShiftLeft(FlowGraphCompiler* compiler,
   }
 
   const bool right_needs_check =
-      (right_range == NULL) || !right_range->IsWithin(0, (Smi::kBits - 1));
+      !RangeUtils::IsWithin(right_range, 0, (Smi::kBits - 1));
   if (is_truncating) {
     if (right_needs_check) {
       const bool right_may_be_negative =