Mojo: Add support for constants to the IDL compiler.

mojo/public/tools/bindings/generators/js_templates/module.js.tmpl

 // Copyright 2013 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.
 
 define("{{module.path}}", [
     "mojo/public/js/bindings/core",
     "mojo/public/js/bindings/codec",
 {%- for import in imports %}
     "{{import.module.path}}",
 {%- endfor %}
   ], function(core, codec
 {%- for import in imports -%}
     , {{import.unique_name}}
 {%- endfor -%}
 ) {
 
+{#--- Constants #}
+{%  for constant in module.constants %}
+  var {{constant.name}} = {{constant.value|expression_to_text(module)}};
+{%- endfor %}
+
 {#--- Enums #}
-{%  from "enum_definition.tmpl" import enum_def -%}
-{%  for enum in enums %}
+{%- from "enum_definition.tmpl" import enum_def %}
+{%- for enum in enums %}
   var {{ enum_def(enum.name, enum, module) }}
 {%-  endfor %}
 
 {#--- Struct definitions #}
 {%  for struct in structs %}
 {%-   include "struct_definition.tmpl" %}
 {%- endfor %}
 
 {#--- Interface definitions #}
 {%- for interface in interfaces %}
 {%-   include "interface_definition.tmpl" %}
 {%- endfor %}
 
   var exports = {};
+{%  for constant in module.constants %}
+  exports.{{constant.name}} = {{constant.name}};
+{%- endfor %}
 {%- for enum in enums %}
   exports.{{enum.name}} = {{enum.name}};
 {%- endfor %}
 {%- for struct in structs if struct.exported %}
   exports.{{struct.name}} = {{struct.name}};
 {%- endfor %}
 {%- for interface in interfaces %}
   exports.{{interface.name}}Proxy = {{interface.name}}Proxy;
   exports.{{interface.name}}Stub = {{interface.name}}Stub;
 {%- endfor %}
   return exports;
 });