[turbofan] Move graph trimming functionality to dedicated GraphTrimmer.

src/compiler/node-marker.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/node-marker.h"
 
 #include "src/compiler/graph.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 NodeMarkerBase::NodeMarkerBase(Graph* graph, uint32_t num_states)
     : mark_min_(graph->mark_max_), mark_max_(graph->mark_max_ += num_states) {
   DCHECK_NE(0u, num_states);        // user error!
   DCHECK_LT(mark_min_, mark_max_);  // check for wraparound.
 }
 
-
-void NodeMarkerBase::Reset(Graph* graph) {
-  uint32_t const num_states = mark_max_ - mark_min_;
-  mark_min_ = graph->mark_max_;
-  mark_max_ = graph->mark_max_ += num_states;
-  DCHECK_LT(mark_min_, mark_max_);  // check for wraparound.
-}
-
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8