[DMC #5.6] Add type cast for SpellCheckMarkerListImpl

third_party/WebKit/Source/core/editing/markers/SpellCheckMarkerListImpl.h

 // Copyright 2017 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 SpellCheckMarkerListImpl_h
 #define SpellCheckMarkerListImpl_h
 
 #include "core/editing/markers/DocumentMarkerList.h"
 
 namespace blink {
@@ skipping 25 matching lines @@
 
  protected:
   SpellCheckMarkerListImpl() = default;
 
  private:
   HeapVector<Member<RenderedDocumentMarker>> markers_;
 
   DISALLOW_COPY_AND_ASSIGN(SpellCheckMarkerListImpl);
 };
 
+DEFINE_TYPE_CASTS(SpellCheckMarkerListImpl,
+                  DocumentMarkerList,
+                  list,
+                  list->MarkerType() == DocumentMarker::kSpelling ||
+                      list->MarkerType() == DocumentMarker::kGrammar,
+                  list.MarkerType() == DocumentMarker::kSpelling ||
+                      list.MarkerType() == DocumentMarker::kGrammar);
+
 }  // namespace blink
 
 #endif  // SpellCheckMarkerListImpl_h