Make ComputedStyleBase use MemberCopy when copying pointer fields.

third_party/WebKit/Source/build/scripts/templates/fields/group.tmpl

 {% from 'fields/field.tmpl' import encode, declare_storage, compare %}
 {% from 'macros.tmpl' import print_if %}
 {% macro define_field_group_class(group): -%}
 class {{group.type_name}} : public RefCounted<{{group.type_name}}> {
  public:
   static PassRefPtr<{{group.type_name}}> Create() {
     return AdoptRef(new {{group.type_name}});
   }
   PassRefPtr<{{group.type_name}}> Copy() const {
     return AdoptRef(new {{group.type_name}}(*this));
@@ skipping 14 matching lines @@
 
  private:
   {{group.type_name}}() :
   {% for field in group.fields %}
       {{field.name}}({{encode(field, field.default_value)}}){{print_if(not loop.last, ',')}}
   {% endfor %}
   {}
 
   {{group.type_name}}(const {{group.type_name}}& other) :
   {% for field in group.fields %}
+      {% if field.wrapper_pointer_name %}
+      {{field.name}}(MemberCopy(other.{{field.name}})){{print_if(not loop.last, ',')}}
+      {% else %}
       {{field.name}}(other.{{field.name}}){{print_if(not loop.last, ',')}}
+      {% endif %}
   {% endfor %}
   {}
 };
 {%- endmacro %}