[runtime] Fancify KeyAccumulator

src/runtime/runtime-object.cc

Index: src/runtime/runtime-object.cc
diff --git a/src/runtime/runtime-object.cc b/src/runtime/runtime-object.cc
index 3d02572a0e0cae4c6a8ef8defcc932bf035d36eb..12dece522f08610cbc5d903f4818d0f62f3e6530 100644
--- a/src/runtime/runtime-object.cc
+++ b/src/runtime/runtime-object.cc
@@ -983,11 +983,7 @@ RUNTIME_FUNCTION(Runtime_OwnKeys) {
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       isolate, contents, JSReceiver::GetKeys(object, JSReceiver::OWN_ONLY));
 
-  // Some fast paths through GetKeysInFixedArrayFor reuse a cached
-  // property array and since the result is mutable we have to create
-  // a fresh clone on each invocation.
   int length = contents->length();
-  Handle<FixedArray> copy = isolate->factory()->NewFixedArray(length);
   int offset = 0;
   // Use an outer loop to avoid creating too many handles in the current
   // handle scope.
@@ -997,18 +993,16 @@ RUNTIME_FUNCTION(Runtime_OwnKeys) {
     int end = Min(offset, length);
     for (int i = offset - 100; i < end; i++) {
       Object* entry = contents->get(i);
-      if (entry->IsString()) {
-        copy->set(i, entry);
-      } else {
-        DCHECK(entry->IsNumber());
-        Handle<Object> entry_handle(entry, isolate);
-        Handle<Object> entry_str =
-            isolate->factory()->NumberToString(entry_handle);
-        copy->set(i, *entry_str);
-      }
+      if (entry->IsString()) continue;
+
+      DCHECK(entry->IsNumber());
+      Handle<Object> entry_handle(entry, isolate);
+      Handle<Object> entry_str =
+          isolate->factory()->NumberToString(entry_handle);
+      contents->set(i, *entry_str);
     }
   }
-  return *isolate->factory()->NewJSArrayWithElements(copy);
+  return *isolate->factory()->NewJSArrayWithElements(contents);
 }