[turbofan] Cache Call operator for AllocateHeapNumberStub in change lowering.

src/compiler/change-lowering.h

 // Copyright 2014 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.
 
 #ifndef V8_COMPILER_CHANGE_LOWERING_H_
 #define V8_COMPILER_CHANGE_LOWERING_H_
 
 #include "src/compiler/graph-reducer.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Forward declarations.
 class CommonOperatorBuilder;
 class JSGraph;
 class Linkage;
 class MachineOperatorBuilder;
+class Operator;
 
 class ChangeLowering FINAL : public Reducer {
  public:
   explicit ChangeLowering(JSGraph* jsgraph) : jsgraph_(jsgraph) {}
   ~ChangeLowering() FINAL;
 
   Reduction Reduce(Node* node) FINAL;
 
  private:
   Node* HeapNumberValueIndexConstant();
@@ skipping 18 matching lines @@
   Reduction ChangeTaggedToUI32(Node* value, Node* control,
                                Signedness signedness);
   Reduction ChangeUint32ToTagged(Node* value, Node* control);
 
   Graph* graph() const;
   Isolate* isolate() const;
   JSGraph* jsgraph() const { return jsgraph_; }
   CommonOperatorBuilder* common() const;
   MachineOperatorBuilder* machine() const;
 
-  JSGraph* jsgraph_;
+  JSGraph* const jsgraph_;
+  SetOncePointer<const Operator> allocate_heap_number_operator_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_CHANGE_LOWERING_H_