fix imports link rel=stylesheet

pkg/polymer/lib/src/build/common.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.
 
 /** Common methods used by transfomers. */
 library polymer.src.build.common;
 
 import 'dart:async';
 import 'dart:math' show min, max;
 
@@ skipping 94 matching lines @@
     var primaryId = transform.primaryInput.id;
     bool samePackage = id.package == primaryId.package;
     var url = samePackage ? id.path
         : assetUrlFor(id, primaryId, transform.logger, allowAssetUrl: true);
     return transform.readInputAsString(id).then((content) {
       return _parseHtml(content, url, transform.logger,
         checkDocType: samePackage && options.isHtmlEntryPoint(id));
     });
   }
 
+  Future<String> readAsString(AssetId id, Transform transform) {

[Siggi Cherem (dart-lang), 2014/02/13 00:08:18]

is this method needed? seems that the first few values are not used, so this is
just doing the same as:
  transform.readInputAsString(id)

[Jennifer Messerly, 2014/02/13 06:11:22]

good catch. Out of curiosity, what is the  `var url = samePackage ? id.path ...`
business for? Should I be using it when I construct a source span -- since it
seems to be passed to the _parseHtml function?

It seems like a lot of complexity compared to just doing an id.path, just to
improve the error message... Does id.path not point at the correct path for a
user to understand a warning?

anyway I moved the URL computation into the place where I'm building the source
spans, so it matches the HTML code path as closely as possible.

[Siggi Cherem (dart-lang), 2014/02/13 17:46:33]

It's basically for better error messages.
Exactly. 
Well, only if you are in the same package. 'id.path' is a relative path from a
package's home dir, so if you have 'lib/foo/bar.dart' in 2 packages, their
id.path is the same.

The basic principle I followed was:
 - if it's on the same package, then use the path (id.path), the user will know
that a path means a file in their own code
 - if it's on another package, then use [assetUrlFor], this will likely be a
"package:" url to the file in the other package, which is enough for users to
identify where the error is.

Unfortunately, [assetUrlFor] doesn't work for the same package because we have
files in 'web' and other folders that don't have a "package:" url. [assetUrlFor]
will produce a relative URL instead.
Cool

[Jennifer Messerly, 2014/02/13 20:43:45]

Lovely explanation! Thank you :)

+    var primaryId = transform.primaryInput.id;
+    bool samePackage = id.package == primaryId.package;
+    var url = samePackage ? id.path
+        : assetUrlFor(id, primaryId, transform.logger, allowAssetUrl: true);
+    return transform.readInputAsString(id);
+  }
+
   Future<bool> assetExists(AssetId id, Transform transform) =>
       transform.getInput(id).then((_) => true).catchError((_) => false);
 
   String toString() => 'polymer ($runtimeType)';
 }
 
 /** Transformer phases which should be applied to the Polymer package. */
 List<List<Transformer>> get phasesForPolymer =>
     [[new ObservableTransformer(['lib/src/instance.dart'])]];
 
 /**
  * Create an [AssetId] for a [url] seen in the [source] asset. By default this
  * is used to resolve relative urls that occur in HTML assets, including
  * cross-package urls of the form "packages/foo/bar.html". Dart-style "package:"
  * urls are not resolved unless [source] is Dart file (has a .dart extension).
  */
 // TODO(sigmund): delete once this is part of barback (dartbug.com/12610)
-AssetId resolve(AssetId source, String url, TransformLogger logger, Span span) {
+AssetId resolve(AssetId source, String url, TransformLogger logger, Span span,
+    {bool allowAbsolute: false}) {
   if (url == null || url == '') return null;
   var uri = Uri.parse(url);
   var urlBuilder = path.url;
   if (uri.host != '' || uri.scheme != '' || urlBuilder.isAbsolute(url)) {
     if (source.extension == '.dart' && uri.scheme == 'package') {
       var index = uri.path.indexOf('/');
       if (index != -1) {
         return new AssetId(uri.path.substring(0, index),
             'lib${uri.path.substring(index)}');
       }
     }
 
-    logger.error('absolute paths not allowed: "$url"', span: span);
+    if (!allowAbsolute) {
+      logger.error('absolute paths not allowed: "$url"', span: span);
+    }

[Siggi Cherem (dart-lang), 2014/02/13 00:08:18]

we might want to resolve more precisely paths that start with '/' but not a
different domain. For now I think this is fine, in the future I think we will
want to treat

/packages/foo/bar

similar to 

packages/foo/bar

[Jennifer Messerly, 2014/02/13 06:11:22]

yeah agree

     return null;
   }
 
   var targetPath = urlBuilder.normalize(
       urlBuilder.join(urlBuilder.dirname(source.path), url));
   var segments = urlBuilder.split(targetPath);
   var sourceSegments = urlBuilder.split(source.path);
   assert (sourceSegments.length > 0);
   var topFolder = sourceSegments[0];
   var entryFolder = topFolder != 'lib' && topFolder != 'asset';
@@ skipping 83 matching lines @@
   return builder.relative(builder.join('/', id.path),
       from: builder.join('/', builder.dirname(sourceId.path)));
 }
 
 
 /** Convert system paths to asset paths (asset paths are posix style). */
 String _systemToAssetPath(String assetPath) {
   if (path.Style.platform != path.Style.windows) return assetPath;
   return path.posix.joinAll(path.split(assetPath));
 }