Consider slots as a focus scope

third_party/WebKit/Source/core/dom/shadow/SlotScopedTraversal.h

Index: third_party/WebKit/Source/core/dom/shadow/SlotScopedTraversal.h
diff --git a/third_party/WebKit/Source/core/dom/shadow/SlotScopedTraversal.h b/third_party/WebKit/Source/core/dom/shadow/SlotScopedTraversal.h
new file mode 100644
index 0000000000000000000000000000000000000000..803aab0da87d2a3d840c98d98a98bfda0428ce94
--- /dev/null
+++ b/third_party/WebKit/Source/core/dom/shadow/SlotScopedTraversal.h
@@ -0,0 +1,24 @@
+// Copyright 2016 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 SlotScopedTraversal_h
+#define SlotScopedTraversal_h
+
+namespace blink {
+
+class Element;
+class HTMLSlotElement;
+
+class SlotScopedTraversal {
+public:
+    static HTMLSlotElement* findScopeOwnerSlot(const Element& current);
+    static Element* nearestAncestorAssignedToSlot(const Element& current);
+    static Element* next(const Element& current);
+    static Element* previous(const Element& current);
+    static bool isSlotScoped(const Element& current);
+};
+
+} // namespace blink
+
+#endif