Fix clang compilation error.

src/arm64/code-stubs-arm64.cc

Index: src/arm64/code-stubs-arm64.cc
diff --git a/src/arm64/code-stubs-arm64.cc b/src/arm64/code-stubs-arm64.cc
index f3fb6ac63ddb8f8fc3aed96cd8524cfd2471ca4f..9056772324e5fb98606d5f4d1be30efbe3e4b369 100644
--- a/src/arm64/code-stubs-arm64.cc
+++ b/src/arm64/code-stubs-arm64.cc
@@ -3125,14 +3125,16 @@ void CallICStub::GenerateMiss(MacroAssembler* masm) {
 
 void StringCharCodeAtGenerator::GenerateFast(MacroAssembler* masm) {
   // If the receiver is a smi trigger the non-string case.
-  __ JumpIfSmi(object_, receiver_not_string_);
+  if (check_mode_ == RECEIVER_IS_UNKNOWN) {
+    __ JumpIfSmi(object_, receiver_not_string_);
 
-  // Fetch the instance type of the receiver into result register.
-  __ Ldr(result_, FieldMemOperand(object_, HeapObject::kMapOffset));
-  __ Ldrb(result_, FieldMemOperand(result_, Map::kInstanceTypeOffset));
+    // Fetch the instance type of the receiver into result register.
+    __ Ldr(result_, FieldMemOperand(object_, HeapObject::kMapOffset));
+    __ Ldrb(result_, FieldMemOperand(result_, Map::kInstanceTypeOffset));
 
-  // If the receiver is not a string trigger the non-string case.
-  __ TestAndBranchIfAnySet(result_, kIsNotStringMask, receiver_not_string_);
+    // If the receiver is not a string trigger the non-string case.
+    __ TestAndBranchIfAnySet(result_, kIsNotStringMask, receiver_not_string_);
+  }
 
   // If the index is non-smi trigger the non-smi case.
   __ JumpIfNotSmi(index_, &index_not_smi_);