Reland of [keys] Simplify KeyAccumulator

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index ee6850b69827fb8cb0476ad89129843eac339c47..f873f9478bcf5964b0fa4b47967c01a772c420db 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -21,8 +21,9 @@
 #include "src/handles-inl.h"
 #include "src/heap/heap-inl.h"
 #include "src/heap/heap.h"
-#include "src/isolate.h"
 #include "src/isolate-inl.h"
+#include "src/isolate.h"
+#include "src/keys.h"
 #include "src/layout-descriptor-inl.h"
 #include "src/lookup.h"
 #include "src/objects.h"
@@ -1110,6 +1111,12 @@ MaybeHandle<Object> JSReceiver::GetProperty(Isolate* isolate,
   return GetProperty(receiver, str);
 }
 
+// static
+MUST_USE_RESULT MaybeHandle<FixedArray> JSReceiver::OwnPropertyKeys(
+    Handle<JSReceiver> object) {
+  return KeyAccumulator::GetKeys(object, OWN_ONLY, ALL_PROPERTIES,
+                                 CONVERT_TO_STRING);
+}
 
 #define FIELD_ADDR(p, offset) \
   (reinterpret_cast<byte*>(p) + offset - kHeapObjectTag)
@@ -6640,16 +6647,18 @@ ElementsKind JSObject::GetElementsKind() {
   // pointer may point to a one pointer filler map.
   if (ElementsAreSafeToExamine()) {
     Map* map = fixed_array->map();
-    DCHECK((IsFastSmiOrObjectElementsKind(kind) &&
-            (map == GetHeap()->fixed_array_map() ||
-             map == GetHeap()->fixed_cow_array_map())) ||
-           (IsFastDoubleElementsKind(kind) &&
-            (fixed_array->IsFixedDoubleArray() ||
-             fixed_array == GetHeap()->empty_fixed_array())) ||
-           (kind == DICTIONARY_ELEMENTS &&
-            fixed_array->IsFixedArray() &&
-            fixed_array->IsDictionary()) ||
-           (kind > DICTIONARY_ELEMENTS));
+    if (IsFastSmiOrObjectElementsKind(kind)) {
+      DCHECK(map == GetHeap()->fixed_array_map() ||
+             map == GetHeap()->fixed_cow_array_map());
+    } else if (IsFastDoubleElementsKind(kind)) {
+      DCHECK(fixed_array->IsFixedDoubleArray() ||
+             fixed_array == GetHeap()->empty_fixed_array());
+    } else if (kind == DICTIONARY_ELEMENTS) {
+      DCHECK(fixed_array->IsFixedArray());
+      DCHECK(fixed_array->IsDictionary());
+    } else {
+      DCHECK(kind > DICTIONARY_ELEMENTS);
+    }
     DCHECK(!IsSloppyArgumentsElements(kind) ||
            (elements()->IsFixedArray() && elements()->length() >= 2));
   }