Improves how to initialize polymer apps and fixes polymer build and linter to

pkg/polymer/lib/src/build/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.build.polyfill_injector;
 
@@ skipping 68 matching lines @@
         // Replace all other Dart script tags with JavaScript versions.
         for (var script in dartScripts) {
           final src = script.attributes['src'];
           if (src.endsWith('.dart')) {
             script.attributes.remove('type');
             script.attributes['src'] = '$src$csp.js';
           }
         }
         // Remove "packages/browser/dart.js"
         if (dartJs != null) dartJs.remove();
+      } else if (dartJs == null) {
+        document.body.nodes.add(parseFragment(
+              '<script src="packages/browser/dart.js"></script>'));
       }
 
       _addScript(urlSegment) {
-        document.body.nodes.insert(0, parseFragment(
+        document.head.nodes.insert(0, parseFragment(
               '<script src="packages/$urlSegment"></script>\n'));
       }
 
       // JS interop code is required for Polymer CSS shimming.
       if (!jsInteropFound) _addScript('browser/interop.js');
       if (!customElementFound) {
         _addScript('custom_element/custom-elements.debug.js');
       }
 
-      // This polyfill needs to be the first one on the body
+      // This polyfill needs to be the first one on the head
       // TODO(jmesserly): this is .debug to workaround issue 13046.
       if (!shadowDomFound) _addScript('shadow_dom/shadow_dom.debug.js');
 
       transform.addOutput(
           new Asset.fromString(transform.primaryInput.id, document.outerHtml));
     });
   }
 }
 
 final _shadowDomJS = new RegExp(r'shadow_dom\..*\.js', caseSensitive: false);
 final _customElementJS = new RegExp(r'custom-elements\..*\.js',
     caseSensitive: false);