Mojom runtime type info: New implementation for Dart.

mojo/public/tools/bindings/generators/dart_templates/enum_definition.tmpl

-{% import "mojom_type_macros.tmpl" as mojom_type_macros %}
-
 {%- macro enum_def(enum, typepkg, package) %}
 class {{enum|name}} extends bindings.MojoEnum {
 {%- for field in enum.fields %}
   static const {{enum|name}} {{field|name}} = const {{enum|name}}._({{field.resolved_value}});
 {%- endfor %}
 
   const {{enum|name}}._(int v) : super(v);
 
   static const Map<String, {{enum|name}}> valuesMap = const {
 {%- for field in enum.fields %}
@@ skipping 36 matching lines @@
         return '{{enum|name}}.{{field|name}}';
 {%- endfor %}
       default:
         return null;
     }
   }
 
   int toJson() => mojoEnumValue;
 }
 
-{% if should_gen_mojom_types -%}
-{{ mojom_type_macros.writeMojomTypeDef(enum, typepkg, package) }}
-{%- endif -%}
 {%- endmacro %}