[turbofan] Make an OptionalOperator for MachineOperatorBuilder.

src/compiler/js-intrinsic-lowering.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/js-intrinsic-lowering.h"
 
 #include <stack>
 
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
@@ skipping 227 matching lines @@
                 value, effect, control);
 }
 
 
 Reduction JSIntrinsicLowering::ReduceMathClz32(Node* node) {
   return Change(node, machine()->Word32Clz());
 }
 
 
 Reduction JSIntrinsicLowering::ReduceMathFloor(Node* node) {
-  if (!machine()->HasFloat64RoundDown()) return NoChange();
-  return Change(node, machine()->Float64RoundDown());
+  if (!machine()->Float64RoundDown().supported()) return NoChange();
+  return Change(node, machine()->Float64RoundDown().op());
 }
 
 
 Reduction JSIntrinsicLowering::ReduceMathSqrt(Node* node) {
   return Change(node, machine()->Float64Sqrt());
 }
 
 
 Reduction JSIntrinsicLowering::ReduceSeqStringGetChar(
     Node* node, String::Encoding encoding) {
@@ skipping 165 matching lines @@
 }
 
 
 MachineOperatorBuilder* JSIntrinsicLowering::machine() const {
   return jsgraph()->machine();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8