A64: Synchronize with r15814.

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index 66bc38b2601e6df026f548dd7fe10c20de03343f..bac4e793b279bf4a86353db7024aa92352219e79 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -3645,7 +3645,7 @@ void FullCodeGenerator::EmitStringAdd(CallRuntime* expr) {
   VisitForStackValue(args->at(0));
   VisitForStackValue(args->at(1));
 
-  StringAddStub stub(NO_STRING_ADD_FLAGS);
+  StringAddStub stub(STRING_ADD_CHECK_BOTH);
   __ CallStub(&stub);
   context()->Plug(rax);
 }
@@ -4420,7 +4420,9 @@ void FullCodeGenerator::VisitCountOperation(CountOperation* expr) {
 
   // Call ToNumber only if operand is not a smi.
   Label no_conversion;
-  __ JumpIfSmi(rax, &no_conversion, Label::kNear);
+  if (ShouldInlineSmiCase(expr->op())) {
+    __ JumpIfSmi(rax, &no_conversion, Label::kNear);
+  }
   ToNumberStub convert_stub;
   __ CallStub(&convert_stub);
   __ bind(&no_conversion);