[turbofan] Remove last_use_ field from Node.

src/compiler/node.h

 // Copyright 2013 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_NODE_H_
 #define V8_COMPILER_NODE_H_
 
 #include "src/compiler/opcodes.h"
 #include "src/compiler/operator.h"
 #include "src/types-inl.h"
@@ skipping 49 matching lines @@
   int InputCount() const { return input_count(); }
   Node* InputAt(int index) const { return GetInputRecordPtr(index)->to; }
   inline void ReplaceInput(int index, Node* new_to);
   void AppendInput(Zone* zone, Node* new_to);
   void InsertInput(Zone* zone, int index, Node* new_to);
   void RemoveInput(int index);
   void RemoveAllInputs();
   void TrimInputCount(int new_input_count);
 
   int UseCount() const;
-  Node* UseAt(int index) const;
   void ReplaceUses(Node* replace_to);
 
   class InputEdges FINAL {
    public:
     typedef Edge value_type;
 
     class iterator;
     inline iterator begin() const;
     inline iterator end() const;
 
@@ skipping 138 matching lines @@
   typedef BitField<unsigned, 29, 2> ReservedInputCountField;
   typedef BitField<unsigned, 31, 1> HasAppendableInputsField;
   static const int kDefaultReservedInputs = ReservedInputCountField::kMax;
 
   const Operator* op_;
   Bounds bounds_;
   Mark mark_;
   NodeId const id_;
   unsigned bit_field_;
   Use* first_use_;
-  Use* last_use_;
   union {
     // When a node is initially allocated, it uses a static buffer to hold its
     // inputs under the assumption that the number of outputs will not increase.
     // When the first input is appended, the static buffer is converted into a
     // deque to allow for space-efficient growing.
     Input static_[1];
     InputDeque* appendable_;
   } inputs_;
 
   friend class Edge;
@@ skipping 238 matching lines @@
 
 void Node::ReplaceInput(int index, Node* new_to) {
   GetInputRecordPtr(index)->Update(new_to);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_NODE_H_