introduce web_components pkg for consolidated polyfills

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

 // 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.
 
 /**
  * Definitions used to run the polymer linter and deploy tools without using
  * pub serve or pub deploy.
  */
 library polymer.src.build.runner;
 
@@ skipping 99 matching lines @@
   var map = JSON.decode(result.stdout)["packages"];
   map.forEach((k, v) { map[k] = path.dirname(v); });
   map[currentPackage] = '.';
   return map;
 }
 
 /** Internal packages used by polymer. */
 // TODO(sigmund): consider computing this list by recursively parsing
 // pubspec.yaml files in the `Options.packageDirs`.
 final Set<String> _polymerPackageDependencies = [
-    'analyzer', 'args', 'barback', 'browser', 'custom_element', 'html5lib',
-    'html_import', 'js', 'logging', 'mutation_observer', 'observe', 'path'
-    'polymer_expressions', 'serialization', 'shadow_dom', 'source_maps',
+    'analyzer', 'args', 'barback', 'browser', 'html5lib',
+    'js', 'logging', 'mutation_observer', 'observe', 'path'
+    'polymer_expressions', 'serialization', 'source_maps',
     'stack_trace', 'template_binding', 'unittest', 'unmodifiable_collection',
-    'yaml'].toSet();
+    'web_components', 'yaml'].toSet();
 
 /** Return the relative path of each file under [subDir] in [package]. */
 Iterable<String> _listPackageDir(String package, String subDir,
     BarbackOptions options) {
   var packageDir = options.packageDirs[package];
   if (packageDir == null) return const [];
   var dir = new Directory(path.join(packageDir, subDir));
   if (!dir.existsSync()) return const [];
   return dir.listSync(recursive: true, followLinks: options.followLinks)
       .where((f) => f is File)
@@ skipping 240 matching lines @@
     output.write(entry.span.getLocationMessage(entry.message,
           useColors: useColors,
           color: levelColor));
   }
   return output.toString();
 }
 
 const String _RED_COLOR = '\u001b[31m';
 const String _MAGENTA_COLOR = '\u001b[35m';
 const String _NO_COLOR = '\u001b[0m';