Revert of [turbofan] Remove left-over change bits from ChangeLowering.

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;
 struct ElementAccess;
 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* SmiShiftBitsConstant();
+
+  Node* ChangeInt32ToSmi(Node* value);
+  Node* ChangeSmiToWord32(Node* value);
+  Node* ChangeUint32ToFloat64(Node* value);
+
+  Reduction ReduceChangeBitToBool(Node* value, Node* control);
+  Reduction ReduceChangeBoolToBit(Node* value);
+  Reduction ReduceChangeInt31ToTagged(Node* value, Node* control);
+  Reduction ReduceChangeTaggedSignedToInt32(Node* value);
+
   Reduction ReduceLoadField(Node* node);
   Reduction ReduceStoreField(Node* node);
   Reduction ReduceLoadElement(Node* node);
   Reduction ReduceStoreElement(Node* node);
   Reduction ReduceAllocate(Node* node);
 
+  Reduction ReduceObjectIsSmi(Node* node);
+
   Node* ComputeIndex(const ElementAccess& access, Node* const key);
   Graph* graph() const;
   Isolate* isolate() const;
   JSGraph* jsgraph() const { return jsgraph_; }
   CommonOperatorBuilder* common() const;
   MachineOperatorBuilder* machine() const;
 
   JSGraph* const jsgraph_;
   SetOncePointer<const Operator> allocate_operator_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_CHANGE_LOWERING_H_