Revert of [turbofan] Optimize string "length" property access based on types.

src/compiler/js-type-feedback-lowering.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_JS_TYPE_FEEDBACK_LOWERING_H_
-#define V8_COMPILER_JS_TYPE_FEEDBACK_LOWERING_H_
-
-#include "src/base/flags.h"
-#include "src/compiler/graph-reducer.h"
-#include "src/compiler/simplified-operator.h"
-
-namespace v8 {
-namespace internal {
-namespace compiler {
-
-// Forward declarations.
-class CommonOperatorBuilder;
-class JSGraph;
-class MachineOperatorBuilder;
-
-
-// Lowers JS-level operators to simplified operators based on type feedback.
-class JSTypeFeedbackLowering final : public AdvancedReducer {
- public:
-  // Various configuration flags to control the operation of this lowering.
-  enum Flag {
-    kNoFlags = 0,
-    kDeoptimizationEnabled = 1 << 0,
-  };
-  typedef base::Flags<Flag> Flags;
-
-  JSTypeFeedbackLowering(Editor* editor, Flags flags, JSGraph* jsgraph);
-  ~JSTypeFeedbackLowering() final {}
-
-  Reduction Reduce(Node* node) final;
-
- private:
-  Reduction ReduceJSLoadNamed(Node* node);
-
-  Factory* factory() const;
-  Flags flags() const { return flags_; }
-  Graph* graph() const;
-  Isolate* isolate() const;
-  JSGraph* jsgraph() const { return jsgraph_; }
-  CommonOperatorBuilder* common() const;
-  MachineOperatorBuilder* machine() const;
-  SimplifiedOperatorBuilder* simplified() { return &simplified_; }
-
-  Flags const flags_;
-  JSGraph* const jsgraph_;
-  SimplifiedOperatorBuilder simplified_;
-
-  DISALLOW_COPY_AND_ASSIGN(JSTypeFeedbackLowering);
-};
-
-DEFINE_OPERATORS_FOR_FLAGS(JSTypeFeedbackLowering::Flags)
-
-}  // namespace compiler
-}  // namespace internal
-}  // namespace v8
-
-#endif  // V8_COMPILER_JS_TYPE_FEEDBACK_LOWERING_H_