x64: Fix clang complain error of unused private field.

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
diff --git a/src/x64/stub-cache-x64.cc b/src/x64/stub-cache-x64.cc
index 8be604fb0bc07ab91ae8b30d969454ae3c3094d2..7b66a5a232e25ef1b164544a7f2a2cf2f1cb4bc7 100644
--- a/src/x64/stub-cache-x64.cc
+++ b/src/x64/stub-cache-x64.cc
@@ -470,11 +470,8 @@ static void GenerateFastApiCall(MacroAssembler* masm,
 
 class CallInterceptorCompiler BASE_EMBEDDED {
  public:
-  CallInterceptorCompiler(CallStubCompiler* stub_compiler,
-                          const ParameterCount& arguments,
-                          Register name)
+  CallInterceptorCompiler(CallStubCompiler* stub_compiler, Register name)
       : stub_compiler_(stub_compiler),
-        arguments_(arguments),
         name_(name) {}
 
   void Compile(MacroAssembler* masm,
@@ -609,7 +606,6 @@ class CallInterceptorCompiler BASE_EMBEDDED {
   }
 
   CallStubCompiler* stub_compiler_;
-  const ParameterCount& arguments_;
   Register name_;
 };
 
@@ -1465,7 +1461,7 @@ Handle<Code> CallStubCompiler::CompileCallInterceptor(Handle<JSObject> object,
   StackArgumentsAccessor args(rsp, arguments());
   __ movp(rdx, args.GetReceiverOperand());
 
-  CallInterceptorCompiler compiler(this, arguments(), rcx);
+  CallInterceptorCompiler compiler(this, rcx);
   compiler.Compile(masm(), object, holder, name, &lookup, rdx, rbx, rdi, rax,
                    &miss);