Set the correct mime types for assets served via pub serve.

sdk/lib/_internal/pub/lib/src/barback/server.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.
 
 library pub.barback.server;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
 import 'package:barback/barback.dart';
+import 'package:mime/mime.dart';
 import 'package:path/path.dart' as path;
 import 'package:stack_trace/stack_trace.dart';
 
 import '../barback.dart';
 import '../log.dart' as log;
 import '../utils.dart';
 
 /// Callback for determining if an asset with [id] should be served or not.
 typedef bool AllowAsset(AssetId id);
 
@@ skipping 85 matching lines @@
     if (allowAsset != null && !allowAsset(id)) {
       _notFound(request, "Asset $id is not available in this configuration.");
       return;
     }
 
     _logRequest(request, "Loading $id");
     barback.getAssetById(id).then((asset) {
       return validateStream(asset.read()).then((stream) {
         _resultsController.add(
             new BarbackServerResult._success(request.uri, id));
+        request.response.headers.add('content-type', lookupMimeType(id.path));

[Bob Nystrom, 2014/02/11 19:11:14]

Hurray for code reuse!

         // TODO(rnystrom): Set content-type based on asset type.
         return Chain.track(request.response.addStream(stream)).then((_) {
           // Log successful requests both so we can provide debugging
           // information and so scheduled_test knows we haven't timed out while
           // loading transformers.
           _logRequest(request, "Served $id");
           request.response.close();
         });
       }).catchError((error, trace) {
         _resultsController.add(
@@ skipping 174 matching lines @@
   bool get isSuccess => error == null;
 
   /// Whether the request was served unsuccessfully.
   bool get isFailure => !isSuccess;
 
   BarbackServerResult._success(this.url, this.id)
       : error = null;
 
   BarbackServerResult._failure(this.url, this.id, this.error);
 }