delete debug only files from output in release mode

pkg/polymer/lib/src/build/remove_sourcemap_comment.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Transformer that removes any sourcemap comments from javascript files.
+library web_components.src.remove_sourcemap_comment;
+
+import 'dart:async';
+import 'package:barback/barback.dart';
+
+/// Transformer that removes any sourcemap comments from javascript files.
+/// Comments should be on their own line in the form: //# sourceMappingURL=*.map
+class RemoveSourcemapComment extends Transformer {
+  BarbackSettings settings;
+
+  RemoveSourcemapComment.asPlugin(this.settings);
+
+  /// Only apply to files in release mode.
+  isPrimary(_) => settings.mode == BarbackMode.RELEASE;
+
+  apply(Transform transform) {
+    var id = transform.primaryInput.id;
+    return transform.readInputAsString(id).then((file) {
+      if (!file.contains(_SOURCE_MAP_COMMENT)) {
+        // Don't create a new asset if there are no changes.
+        transform.addOutput(transform.primaryInput);

[Siggi Cherem (dart-lang), 2014/09/03 19:20:30]

oh, I meant that by removing the `consume` we also don't need the body of this
branch. This can just be:
if (file.contains(_...)) {
  transform.addOutput(... replaceAll...);
}

[jakemac, 2014/09/03 19:52:47]

Done.

+        return;
+      }
+      transform.addOutput(new Asset.fromString(
+          id, file.replaceAll(_SOURCE_MAP_COMMENT, '')));
+    });
+  }
+}
+
+final RegExp _SOURCE_MAP_COMMENT = new RegExp(r'\n\s*\/\/# sourceMappingURL.*');