Remove unused Zone argument from InitializeAstVisitor

test/cctest/expression-type-collector.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_EXPRESSION_TYPE_COLLECTOR_H_
 #define V8_EXPRESSION_TYPE_COLLECTOR_H_
 
 #include "src/ast-expression-visitor.h"
 
 namespace v8 {
 namespace internal {
 
 // A Visitor over an AST that collects a human readable string summarizing
 // structure and types. Used for testing of the typing information attached
 // to the expression nodes of an AST.
 
 struct ExpressionTypeEntry {
   int depth;
   const char* kind;
   const AstRawString* name;
   Bounds bounds;
 };
 
 class ExpressionTypeCollector : public AstExpressionVisitor {
  public:
-  ExpressionTypeCollector(Isolate* isolate, Zone* zone, FunctionLiteral* root,
+  ExpressionTypeCollector(Isolate* isolate, FunctionLiteral* root,
                           ZoneVector<ExpressionTypeEntry>* dst);
   void Run();
 
  protected:
   void VisitExpression(Expression* expression);
 
  private:
   ZoneVector<ExpressionTypeEntry>* result_;
 };
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_EXPRESSION_TYPE_COLLECTOR_H_