Only generate code for files that are specified, not their imports.

mojo/dart/packages/mojom/lib/src/generate.dart

 // Copyright 2015 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.
 
 /// This library generates Mojo bindings for a Dart package.
 
 library generate;
 
 import 'dart:async';
 import 'dart:convert';
@@ skipping 152 matching lines @@
 
       final arguments = [
         '--use_bundled_pylibs',
         '-g',
         'dart',
         '-o',
         output,
         '-I',
         sdkInc,
         '-I',
-        importDir.path
+        importDir.path,
+        '--no-gen-imports'
       ];
       if (servicesPath != null) {
         arguments.add('-I');
         arguments.add(servicesPath);
       }
       arguments.add(mojom.path);
 
       log.info('Generating $mojom');
       log.info('$script ${arguments.join(" ")}');
       log.info('dryRun = $_dryRun');
@@ skipping 252 matching lines @@
             '\t$dart $packRoot $scriptPath single -m $mojoSdk -r $root '
             '-p $packagePath $skips');
         _errors++;
         return;
       }
     }
   }
 
   bool _shouldSkip(File f) => containsPrefix(f.path, _skip);
 }