Expand usage of defaultEncoding in HttpBody in the http_server package.

pkg/http_server/lib/src/http_multipart_form_data_impl.dart

Index: pkg/http_server/lib/src/http_multipart_form_data_impl.dart
diff --git a/pkg/http_server/lib/src/http_multipart_form_data_impl.dart b/pkg/http_server/lib/src/http_multipart_form_data_impl.dart
index 7956c0f0bb3400bacda1fac8db0170943f6ab30c..91f34fcc6d84ea0866feb3f7989c0f7f73333c27 100644
--- a/pkg/http_server/lib/src/http_multipart_form_data_impl.dart
+++ b/pkg/http_server/lib/src/http_multipart_form_data_impl.dart
@@ -19,7 +19,8 @@ class _HttpMultipartFormData extends Stream implements HttpMultipartFormData {
   _HttpMultipartFormData(ContentType this.contentType,
                          HeaderValue this.contentDisposition,
                          HeaderValue this.contentTransferEncoding,
-                         MimeMultipart this._mimeMultipart) {
+                         MimeMultipart this._mimeMultipart,
+                         Encoding defaultEncoding) {
     _stream = _mimeMultipart;
     if (contentTransferEncoding != null) {
       // TODO(ajohnsen): Support BASE64, etc.
@@ -36,7 +37,7 @@ class _HttpMultipartFormData extends Stream implements HttpMultipartFormData {
       if (contentType != null) {
         encoding = Encoding.getByName(contentType.charset);
       }
-      if (encoding == null) encoding = LATIN1;
+      if (encoding == null) encoding = defaultEncoding;
       _stream = _stream
           .transform(encoding.decoder)
           .expand((data) {
@@ -54,7 +55,8 @@ class _HttpMultipartFormData extends Stream implements HttpMultipartFormData {
   bool get isText => _isText;
   bool get isBinary => !_isText;
 
-  static HttpMultipartFormData parse(MimeMultipart multipart) {
+  static HttpMultipartFormData parse(MimeMultipart multipart,
+                                     Encoding defaultEncoding) {
     var type;
     var encoding;
     var disposition;
@@ -82,7 +84,8 @@ class _HttpMultipartFormData extends Stream implements HttpMultipartFormData {
       throw new HttpException(
           "Mime Multipart doesn't contain a Content-Disposition header value");
     }
-    return new _HttpMultipartFormData(type, disposition, encoding, multipart);
+    return new _HttpMultipartFormData(
+        type, disposition, encoding, multipart, defaultEncoding);
   }
 
   StreamSubscription listen(void onData(data),