Fix read/write of binary assets in deploy

pkg/polymer/lib/deploy.dart

Index: pkg/polymer/lib/deploy.dart
diff --git a/pkg/polymer/lib/deploy.dart b/pkg/polymer/lib/deploy.dart
index 5706463a4a76c909407b9e3f8cfd7500c543fb7f..86f157ba1ee3dd7cf3e8408fee8279ca9887b854 100644
--- a/pkg/polymer/lib/deploy.dart
+++ b/pkg/polymer/lib/deploy.dart
@@ -118,8 +118,8 @@ Future _emitAllFiles(Barback barback, String outDir) {
       }
 
       _ensureDir(path.dirname(filepath));
-      futures.add(asset.readAsString()
-        .then((content) => new File(filepath).writeAsStringSync(content)));

[Siggi Cherem (dart-lang), 2013/08/27 16:54:28]

turns out I was reading a .png file this way, yikes!

The change of the default utf8 encoder to be non-lenient helped detect this.

+      var writer = new File(filepath).openWrite();
+      futures.add(writer.addStream(asset.read()).then((_) => writer.close()));
     }
     return Future.wait(futures);
   }).then((_) {