[turbofan] Simplify escape analysis VerifyReplacement.

src/compiler/escape-analysis-reducer.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_ESCAPE_ANALYSIS_REDUCER_H_
 #define V8_COMPILER_ESCAPE_ANALYSIS_REDUCER_H_
 
 #include "src/bit-vector.h"
 #include "src/compiler/escape-analysis.h"
 #include "src/compiler/graph-reducer.h"
 
-
 namespace v8 {
 namespace internal {
-
-// Forward declarations.
-class Counters;
-
-
 namespace compiler {
 
 // Forward declarations.
 class JSGraph;
 
-
 class EscapeAnalysisReducer final : public AdvancedReducer {
  public:
   EscapeAnalysisReducer(Editor* editor, JSGraph* jsgraph,
                         EscapeAnalysis* escape_analysis, Zone* zone);
 
   Reduction Reduce(Node* node) final;
+
+  // Verifies that all virtual allocation nodes have been dealt with. Run it
+  // after this reducer has been applied. Has no effect in release mode.
   void VerifyReplacement() const;
 
  private:
   Reduction ReduceLoad(Node* node);
   Reduction ReduceStore(Node* node);
   Reduction ReduceAllocate(Node* node);
   Reduction ReduceFinishRegion(Node* node);
   Reduction ReduceReferenceEqual(Node* node);
   Reduction ReduceObjectIsSmi(Node* node);
   Reduction ReduceFrameStateUses(Node* node);
   Node* ReduceDeoptState(Node* node, Node* effect, bool multiple_users);
   Node* ReduceStateValueInput(Node* node, int node_index, Node* effect,
                               bool node_multiused, bool already_cloned,
                               bool multiple_users);
 
   JSGraph* jsgraph() const { return jsgraph_; }
   EscapeAnalysis* escape_analysis() const { return escape_analysis_; }
   Zone* zone() const { return zone_; }
-  Counters* counters() const;
+  Isolate* isolate() const;
 
   JSGraph* const jsgraph_;
   EscapeAnalysis* escape_analysis_;
   Zone* const zone_;
-  // _visited marks nodes we already processed (allocs, loads, stores)
+  // This bit vector marks nodes we already processed (allocs, loads, stores)
   // and nodes that do not need a visit from ReduceDeoptState etc.
   BitVector fully_reduced_;
   bool exists_virtual_allocate_;
 
   DISALLOW_COPY_AND_ASSIGN(EscapeAnalysisReducer);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_ESCAPE_ANALYSIS_REDUCER_H_