Make PaintImages a class and implement a Clone() method.

third_party/WebKit/Source/core/style/StyleRareNonInheritedData.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 159 matching lines @@
       text_decoration_color_(o.text_decoration_color_),
       visited_link_text_decoration_color_(
           o.visited_link_text_decoration_color_),
       visited_link_background_color_(o.visited_link_background_color_),
       visited_link_outline_color_(o.visited_link_outline_color_),
       visited_link_border_left_color_(o.visited_link_border_left_color_),
       visited_link_border_right_color_(o.visited_link_border_right_color_),
       visited_link_border_top_color_(o.visited_link_border_top_color_),
       visited_link_border_bottom_color_(o.visited_link_border_bottom_color_),
       callback_selectors_(o.callback_selectors_),
-      paint_images_(o.paint_images_
-                        ? new Vector<Persistent<StyleImage>>(*o.paint_images_)
-                        : nullptr),
+      paint_images_(o.paint_images_ ? new PaintImages(*o.paint_images_)
+                                    : nullptr),
       variables_(o.variables_ ? o.variables_->Clone() : nullptr),
       align_content_(o.align_content_),
       align_items_(o.align_items_),
       align_self_(o.align_self_),
       justify_content_(o.justify_content_),
       justify_items_(o.justify_items_),
       justify_self_(o.justify_self_),
       page_size_type_(o.page_size_type_),
       transform_style_3d_(o.transform_style_3d_),
       backface_visibility_(o.backface_visibility_),
@@ skipping 99 matching lines @@
          requires_accelerated_compositing_for_external_reasons_ ==
              o.requires_accelerated_compositing_for_external_reasons_ &&
          has_inline_transform_ == o.has_inline_transform_ &&
          resize_ == o.resize_ &&
          has_compositor_proxy_ == o.has_compositor_proxy_ &&
          has_author_background_ == o.has_author_background_ &&
          has_author_border_ == o.has_author_border_;
 }
 
 }  // namespace blink