Adding visitors to regurgitate expression types or reset them.

src/ast-expression-visitor.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_AST_EXPRESSION_VISITOR_H_
+#define V8_AST_EXPRESSION_VISITOR_H_
+
+#include "src/allocation.h"
+#include "src/ast.h"
+#include "src/effects.h"
+#include "src/scopes.h"
+#include "src/type-info.h"
+#include "src/types.h"
+#include "src/zone.h"
+
+namespace v8 {
+namespace internal {
+
+// A Visitor over a CompilationInfo's AST that invokes
+// VisitExpression on each expression node.
+
+class AstExpressionVisitor : public AstVisitor {
+ public:
+  explicit AstExpressionVisitor(CompilationInfo* info);
+  void Run();
+
+ protected:
+  virtual void VisitExpression(Expression* expression) = 0;
+  int depth() { return depth_; }
+
+ private:
+  void VisitDeclarations(ZoneList<Declaration*>* d) override;
+  void VisitStatements(ZoneList<Statement*>* s) override;
+
+  DEFINE_AST_VISITOR_SUBCLASS_MEMBERS();
+
+#define DECLARE_VISIT(type) virtual void Visit##type(type* node) override;
+  AST_NODE_LIST(DECLARE_VISIT)
+#undef DECLARE_VISIT
+
+  CompilationInfo* compilation_info_;
+  int depth_;
+
+  DISALLOW_COPY_AND_ASSIGN(AstExpressionVisitor);
+};
+}
+}  // namespace v8::internal
+
+#endif  // V8_AST_EXPRESSION_VISITOR_H_