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diff --git a/deps/v8/src/keys.h b/deps/v8/src/keys.h
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+++ b/deps/v8/src/keys.h
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+// Copyright 2012 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_KEY_ACCUMULATOR_H_
+#define V8_KEY_ACCUMULATOR_H_
+
+#include "src/isolate.h"
+#include "src/objects.h"
+
+namespace v8 {
+namespace internal {
+
+enum AddKeyConversion { DO_NOT_CONVERT, CONVERT_TO_ARRAY_INDEX, PROXY_MAGIC };
+
+// This is a helper class for JSReceiver::GetKeys which collects and sorts keys.
+// GetKeys needs to sort keys per prototype level, first showing the integer
+// indices from elements then the strings from the properties. However, this
+// does not apply to proxies which are in full control of how the keys are
+// sorted.
+//
+// For performance reasons the KeyAccumulator internally separates integer keys
+// in |elements_| into sorted lists per prototype level. String keys are
+// collected in |string_properties_|, a single OrderedHashSet (similar for
+// Symbols in |symbol_properties_|. To separate the keys per level later when
+// assembling the final list, |levelLengths_| keeps track of the number of
+// String and Symbol keys per level.
+//
+// Only unique keys are kept by the KeyAccumulator, strings are stored in a
+// HashSet for inexpensive lookups. Integer keys are kept in sorted lists which
+// are more compact and allow for reasonably fast includes check.
+class KeyAccumulator final BASE_EMBEDDED {
+ public:
+  KeyAccumulator(Isolate* isolate, KeyCollectionType type,
+                 PropertyFilter filter)
+      : isolate_(isolate), type_(type), filter_(filter) {}
+  ~KeyAccumulator();
+
+  bool AddKey(uint32_t key);
+  bool AddKey(Object* key, AddKeyConversion convert);
+  bool AddKey(Handle<Object> key, AddKeyConversion convert);
+  void AddKeys(Handle<FixedArray> array, AddKeyConversion convert);
+  void AddKeys(Handle<JSObject> array, AddKeyConversion convert);
+  void AddKeysFromProxy(Handle<JSObject> array);
+  Maybe<bool> AddKeysFromProxy(Handle<JSProxy> proxy, Handle<FixedArray> keys);
+  void AddElementKeysFromInterceptor(Handle<JSObject> array);
+  // Jump to the next level, pushing the current |levelLength_| to
+  // |levelLengths_| and adding a new list to |elements_|.
+  void NextPrototype();
+  // Sort the integer indices in the last list in |elements_|
+  void SortCurrentElementsList();
+  Handle<FixedArray> GetKeys(GetKeysConversion convert = KEEP_NUMBERS);
+  int length() { return length_; }
+  Isolate* isolate() { return isolate_; }
+  void set_filter_proxy_keys(bool filter) { filter_proxy_keys_ = filter; }
+
+ private:
+  bool AddIntegerKey(uint32_t key);
+  bool AddStringKey(Handle<Object> key, AddKeyConversion convert);
+  bool AddSymbolKey(Handle<Object> array);
+  void SortCurrentElementsListRemoveDuplicates();
+
+  Isolate* isolate_;
+  KeyCollectionType type_;
+  PropertyFilter filter_;
+  bool filter_proxy_keys_ = true;
+  // |elements_| contains the sorted element keys (indices) per level.
+  std::vector<std::vector<uint32_t>*> elements_;
+  // |protoLengths_| contains the total number of keys (elements + properties)
+  // per level. Negative values mark counts for a level with keys from a proxy.
+  std::vector<int> level_lengths_;
+  // |string_properties_| contains the unique String property keys for all
+  // levels in insertion order per level.
+  Handle<OrderedHashSet> string_properties_;
+  // |symbol_properties_| contains the unique Symbol property keys for all
+  // levels in insertion order per level.
+  Handle<OrderedHashSet> symbol_properties_;
+  Handle<FixedArray> ownProxyKeys_;
+  // |length_| keeps track of the total number of all element and property keys.
+  int length_ = 0;
+  // |levelLength_| keeps track of the number of String keys in the current
+  // level.
+  int level_string_length_ = 0;
+  // |levelSymbolLength_| keeps track of the number of Symbol keys in the
+  // current level.
+  int level_symbol_length_ = 0;
+
+  DISALLOW_COPY_AND_ASSIGN(KeyAccumulator);
+};
+
+// The FastKeyAccumulator handles the cases where there are no elements on the
+// prototype chain and forwords the complex/slow cases to the normal
+// KeyAccumulator.
+class FastKeyAccumulator {
+ public:
+  FastKeyAccumulator(Isolate* isolate, Handle<JSReceiver> receiver,
+                     KeyCollectionType type, PropertyFilter filter)
+      : isolate_(isolate), receiver_(receiver), type_(type), filter_(filter) {
+    Prepare();
+    // TODO(cbruni): pass filter_ directly to the KeyAccumulator.
+    USE(filter_);
+  }
+
+  bool is_receiver_simple_enum() { return is_receiver_simple_enum_; }
+  bool has_empty_prototype() { return has_empty_prototype_; }
+  void set_filter_proxy_keys(bool filter) { filter_proxy_keys_ = filter; }
+
+  MaybeHandle<FixedArray> GetKeys(GetKeysConversion convert = KEEP_NUMBERS);
+
+ private:
+  void Prepare();
+  MaybeHandle<FixedArray> GetKeysFast(GetKeysConversion convert);
+  MaybeHandle<FixedArray> GetKeysSlow(GetKeysConversion convert);
+
+  Isolate* isolate_;
+  Handle<JSReceiver> receiver_;
+  KeyCollectionType type_;
+  PropertyFilter filter_;
+  bool is_receiver_simple_enum_ = false;
+  bool has_empty_prototype_ = false;
+  bool filter_proxy_keys_ = true;
+
+  DISALLOW_COPY_AND_ASSIGN(FastKeyAccumulator);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_KEY_ACCUMULATOR_H_