[turbofan] Move graph trimming functionality to dedicated GraphTrimmer.

src/compiler/node-marker.h

 // 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.
 
 #ifndef V8_COMPILER_NODE_MARKER_H_
 #define V8_COMPILER_NODE_MARKER_H_
 
 #include "src/compiler/node.h"
 
 namespace v8 {
@@ skipping 16 matching lines @@
       node->set_mark(mark_min_);
     }
     DCHECK_LT(mark, mark_max_);
     return mark - mark_min_;
   }
   V8_INLINE void Set(Node* node, Mark mark) {
     DCHECK_LT(mark, mark_max_ - mark_min_);
     DCHECK_LT(node->mark(), mark_max_);
     node->set_mark(mark + mark_min_);
   }
-  void Reset(Graph* graph);
 
  private:
-  Mark mark_min_;
-  Mark mark_max_;
+  Mark const mark_min_;
+  Mark const mark_max_;
 
   DISALLOW_COPY_AND_ASSIGN(NodeMarkerBase);
 };
 
 
 // A NodeMarker uses monotonically increasing marks to assign local "states"
 // to nodes. Only one NodeMarker per graph is valid at a given time.
 template <typename State>
 class NodeMarker : public NodeMarkerBase {
  public:
   V8_INLINE NodeMarker(Graph* graph, uint32_t num_states)
       : NodeMarkerBase(graph, num_states) {}
 
   V8_INLINE State Get(Node* node) {
     return static_cast<State>(NodeMarkerBase::Get(node));
   }
 
   V8_INLINE void Set(Node* node, State state) {
     NodeMarkerBase::Set(node, static_cast<Mark>(state));
   }
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_NODE_MARKER_H_