Add a change for r19194 that got eaten in a merge.

pkg/http/lib/src/multipart_file.dart

Index: pkg/http/lib/src/multipart_file.dart
diff --git a/pkg/http/lib/src/multipart_file.dart b/pkg/http/lib/src/multipart_file.dart
index 0246c0748c6a27e4eeca54b84abc51638fbaa960..aa30fc350989bd82a6a98f7e92e13ae6696ef45b 100644
--- a/pkg/http/lib/src/multipart_file.dart
+++ b/pkg/http/lib/src/multipart_file.dart
@@ -80,14 +80,15 @@ class MultipartFile {
   }
 
   // TODO(nweiz): Infer the content-type from the filename.
-  /// Creates a new [MultipartFile] from a [File].
+  /// Creates a new [MultipartFile] from a path to a file on disk.
   ///
-  /// [filename] defaults to the name of the file on disk. [contentType]
-  /// currently defaults to `application/octet-stream`, but in the future may be
-  /// inferred from [filename].
-  static Future<MultipartFile> fromFile(String field, File file,
+  /// [filename] defaults to the basename of [filePath]. [contentType] currently
+  /// defaults to `application/octet-stream`, but in the future may be inferred
+  /// from [filename].
+  static Future<MultipartFile> fromPath(String field, String filePath,
       {String filename, ContentType contentType}) {
-    if (filename == null) filename = new Path(file.name).filename;
+    if (filename == null) filename = path.basename(filePath);
+    var file = new File(filePath);
     return file.length().then((length) {
       var stream = new ByteStream(file.openRead());
       return new MultipartFile(field, stream, length,