[key-accumulator] Starting to reimplement the key-accumulator

src/key-accumulator.h

Index: src/key-accumulator.h
diff --git a/src/key-accumulator.h b/src/key-accumulator.h
index 9daee10cd357bf758340f143958b4d0862c45519..0abc37b027f18661b0a2c7a6c16d9f9bb9381be7 100644
--- a/src/key-accumulator.h
+++ b/src/key-accumulator.h
@@ -86,6 +86,35 @@ class KeyAccumulator final BASE_EMBEDDED {
   DISALLOW_COPY_AND_ASSIGN(KeyAccumulator);
 };
 
+class FastKeyAccumulator {
+ public:
+  FastKeyAccumulator(Isolate* isolate, Handle<JSReceiver> receiver,
+                     KeyCollectionType type, PropertyFilter filter)
+      : isolate_(isolate), receiver_(receiver), type_(type), filter_(filter) {
+    Prepare();
+  }
+
+  void UseVars();
+
+  bool is_simple_enum() { return is_simple_enum_; }
+  bool has_empty_prototype() { return has_empty_prototype_; }
+
+  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_simple_enum_ = false;
+  bool has_empty_prototype_ = false;
+
+  DISALLOW_COPY_AND_ASSIGN(FastKeyAccumulator);
+};
 
 }  // namespace internal
 }  // namespace v8