Sibling invalidation sets

Source/core/css/invalidation/InvalidationLists.h

Index: Source/core/css/invalidation/InvalidationLists.h
diff --git a/Source/core/css/invalidation/InvalidationLists.h b/Source/core/css/invalidation/InvalidationLists.h
new file mode 100644
index 0000000000000000000000000000000000000000..e59eb81f54592b2db718808cb551d5e91b9a0f2e
--- /dev/null
+++ b/Source/core/css/invalidation/InvalidationLists.h
@@ -0,0 +1,29 @@
+// Copyright 2015 The Chromium 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 InvalidationLists_h
+#define InvalidationLists_h
+
+#include "core/css/invalidation/InvalidationData.h"
+
+namespace blink {
+
+class CORE_EXPORT InvalidationLists final {
+    WTF_MAKE_NONCOPYABLE(InvalidationLists);
+public:
+    InvalidationLists() {}
+
+    InvalidationSetVector& descendants() { return m_descendants; }
+    const InvalidationSetVector& descendants() const { return m_descendants; }
+    InvalidationSetVector& siblings() { return m_siblings; }
+    const InvalidationSetVector& siblings() const { return m_siblings; }
+
+private:
+    InvalidationSetVector m_descendants;
+    InvalidationSetVector m_siblings;
+};
+
+} // namespace blink
+
+#endif // InvalidationLists_h