Prune the old deploy code. This CL does a few changes:

pkg/polymer/lib/src/transform/polyfill_injector.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.
+
+/**
+ * Final phase of the polymer transformation: includes any additional polyfills
+ * that may needed by the deployed app.
+ */
+library polymer.src.transform.polyfill_injector;
+
+import 'dart:async';
+
+import 'package:barback/barback.dart';
+import 'package:html5lib/dom.dart' show Document, Node, DocumentFragment;
+import 'package:html5lib/parser.dart' show parseFragment;
+import 'common.dart';
+
+/**
+ * Ensures that any scripts and polyfills needed to run a polymer application
+ * are included. For example, this transformer will ensure that there is a
+ * script tag that loads the shadow_dom polyfill and interop.js (used for the
+ * css shimming).
+ */
+class PolyfillInjector extends Transformer {
+  /** Only run this transformer on .html files. */
+  final String allowedExtensions = ".html";
+
+  Future apply(Transform transform) {
+    var id = transform.primaryId;
+    return getPrimaryContent(transform).then((content) {
+      var document = parseHtml(content, id.path, transform.logger);
+      bool shadowDomFound = false;
+      bool jsInteropFound = false;
+      bool dartScriptTags = false;
+
+      for (var tag in document.queryAll('script')) {
+        var src = tag.attributes['src'];
+        if (src != null) {
+          var last = src.split('/').last;
+          if (last == 'interop.js') {
+            jsInteropFound = true;
+          } else if (_shadowDomJS.hasMatch(last)) {
+            shadowDomFound = true;
+          }
+        }
+
+        if (tag.attributes['type'] == 'application/dart') {
+          dartScriptTags = true;
+        }
+      }
+
+      if (!dartScriptTags) {
+        // This HTML has no Dart code, there is nothing to do here.
+        transform.addOutput(new Asset.fromString(id, content));
+        return;
+      }
+
+      if (!jsInteropFound) {
+        // JS interop code is required for Polymer CSS shimming.
+        document.body.nodes.insert(0, parseFragment(
+            '<script type="text/javascript" '

[Jennifer Messerly, 2013/08/28 22:25:45]

could we leave off the type here?

[Siggi Cherem (dart-lang), 2013/08/28 23:17:06]

Done.

+            'src="packages/browser/interop.js"></script>\n'));
+      }
+
+      if (!shadowDomFound) {
+        // Insert at the beginning (this polyfill needs to run as early as
+        // possible).
+        document.body.nodes.insert(0, parseFragment(
+            '<script type="text/javascript" '
+            'src="packages/shadow_dom/shadow_dom.min.js"></script>\n'));
+      }
+
+      transform.addOutput(new Asset.fromString(id, document.outerHtml));
+    });
+  }
+}
+
+final _shadowDomJS = new RegExp(r'shadow_dom\..*\.js', caseSensitive: false);