mojo: Generate top level enums for python bindings.

mojo/public/interfaces/bindings/tests/sample_import.mojom

 // Copyright 2014 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.
 
 [JavaPackage="org.chromium.mojo.bindings.test.mojom.imported"]
 module imported {
 
 // This sample just defines some types that are imported into
 // sample_service.mojom, to show how import works.
 
 enum Shape {
   RECTANGLE = 1,
   CIRCLE,
   TRIANGLE,
+  LAST = TRIANGLE,
 };
 
 // These enum values should not interfere with those of Shape above.
 enum AnotherShape {
   RECTANGLE = 10,
   CIRCLE,
   TRIANGLE,
 };
 
 enum YetAnotherShape {
   RECTANGLE = 20,
   CIRCLE,
   TRIANGLE,
 };
 
 struct Point {
   int32 x;
   int32 y;
 };
 
 interface ImportedInterface {
   DoSomething();
 };
 
 }  // module imported