[DMC #25] Make DocumentMarker::GetType() virtual

third_party/WebKit/Source/core/editing/markers/SpellCheckMarker.cpp

 // 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.
 
 #include "core/editing/markers/SpellCheckMarker.h"
 
 namespace blink {
 
-SpellCheckMarker::SpellCheckMarker(DocumentMarker::MarkerType type,
-                                   unsigned start_offset,
+SpellCheckMarker::SpellCheckMarker(unsigned start_offset,
                                    unsigned end_offset,
                                    const String& description)
-    : DocumentMarker(type, start_offset, end_offset),
-      description_(description) {}
+    : DocumentMarker(start_offset, end_offset), description_(description) {}
 
 const String& SpellCheckMarker::Description() const {
   return description_;
 }
 
 }  // namespace blink