Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/polymer/src/build/build_filter.dart

Index: observatory_pub_packages/polymer/src/build/build_filter.dart
===================================================================
--- observatory_pub_packages/polymer/src/build/build_filter.dart	(revision 0)
+++ observatory_pub_packages/polymer/src/build/build_filter.dart	(working copy)
@@ -0,0 +1,51 @@
+// Copyright (c) 2013, 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.
+
+/// Final phase of the polymer transformation: removes any files that are not
+/// needed for deployment.
+library polymer.src.build.build_filter;
+
+import 'dart:async';
+
+import 'package:barback/barback.dart';
+import 'package:code_transformers/messages/build_logger.dart';
+import 'common.dart';
+
+/// Removes any files not needed for deployment, such as internal build
+/// artifacts and non-entry HTML files.
+class BuildFilter extends Transformer with PolymerTransformer {
+  final TransformOptions options;
+  BuildFilter(this.options);
+
+  isPrimary(AssetId id) {
+    // nothing is filtered in debug mode
+    return options.releaseMode &&
+      // TODO(sigmund): remove this exclusion once we have dev_transformers
+      // (dartbug.com/14187)
+      !id.path.startsWith('lib/') &&
+      // may filter non-entry HTML files and internal artifacts
+      (id.extension == '.html' || id.extension == _DATA_EXTENSION) &&
+      // keep any entry points
+      !options.isHtmlEntryPoint(id);
+  }
+
+  apply(Transform transform) {
+    transform.consumePrimary();
+    if (transform.primaryInput.id.extension == _DATA_EXTENSION) {
+      return null;
+    }
+    var logger = new BuildLogger(transform,
+        convertErrorsToWarnings: !options.releaseMode,
+          detailsUri: 'http://goo.gl/5HPeuP');
+    return readPrimaryAsHtml(transform, logger).then((document) {
+      // Keep .html files that don't use polymer, since the app developer might
+      // have non-polymer entrypoints.
+      if (document.querySelectorAll('polymer-element').isEmpty) {
+        transform.addOutput(transform.primaryInput);
+      }
+    });
+  }
+}
+
+const String _DATA_EXTENSION = '._data';