bindings: Use forward declarations for wrapper types in dictionary_impl

third_party/WebKit/Source/bindings/templates/dictionary_impl.h.tmpl

 {% filter format_blink_cpp_source_code %}
 
 {% include 'copyright_block.txt' %}
 #ifndef {{cpp_class}}_h
 #define {{cpp_class}}_h
 
 {% for filename in header_includes %}
 #include "{{filename}}"
 {% endfor %}
 
 namespace blink {
 
+{% for decl in header_forward_decls %}
+class {{decl}};
+{% endfor %}
+
 {# FIXME: Add "final" if this class doesn\'t have subclasses #}
 class {{exported}}{{cpp_class}}{% if parent_cpp_class %} : public {{parent_cpp_class}}{% endif %} {
   DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
  public:
   {{cpp_class}}();
   virtual ~{{cpp_class}}();
+  {{cpp_class}}(const {{cpp_class}}&);
+  {{cpp_class}}& operator=(const {{cpp_class}}&);
 
   {% for member in members %}
   bool {{member.has_method_name}}() const;
   {{member.rvalue_cpp_type}} {{member.cpp_name}}() const;
   void {{member.setter_name}}({{member.rvalue_cpp_type}});
   {% if member.null_setter_name %}
   void {{member.null_setter_name}}();
   {% endif %}
 
   {% endfor %}
   v8::Local<v8::Value> toV8Impl(v8::Local<v8::Object>, v8::Isolate*) const override;
   DECLARE_VIRTUAL_TRACE();
 
  private:
   {% for member in members %}
   {% if member.nullable_indicator_name %}
   bool {{member.nullable_indicator_name}} = false;
   {% endif %}
   {{member.member_cpp_type}} m_{{member.cpp_name}};
   {% endfor %}
 
   friend class V8{{cpp_class}};
 };
 
 }  // namespace blink
 
 #endif  // {{cpp_class}}_h
 
 {% endfilter %}{# format_blink_cpp_source_code #}