assets: Apply gofmt using Go 1.11.

This fixes a gofmt formatting incompatibility with Go 1.11.
dmitshur committed 3 weeks ago commit 5af16e21babb2483897184bb2e4c97d642af158d
@@ -109,11 +109,11 @@ func (fs vfsgen۰FS) Open(path string) (http.File, error) {
 			// This should never happen because we generate the gzip bytes such that they are always valid.
 			panic("unexpected error reading own gzip compressed bytes: " + err.Error())
 		return &vfsgen۰CompressedFile{
 			vfsgen۰CompressedFileInfo: f,
-			gr: gr,
+			gr:                        gr,
 		}, nil
 	case *vfsgen۰DirInfo:
 		return &vfsgen۰Dir{
 			vfsgen۰DirInfo: f,
 		}, nil