[Mac] Delete more bookmark bar folder code. This removes things that were missed last time.

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_button_cell_unittest.mm

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "base/memory/scoped_nsobject.h"
-#import "chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_button_cell.h"
-#import "chrome/browser/ui/cocoa/cocoa_test_helper.h"
-
-namespace {
-
-class BookmarkBarFolderButtonCellTest : public CocoaTest {
-};
-
-// Basic creation.
-TEST_F(BookmarkBarFolderButtonCellTest, Create) {
-  scoped_nsobject<BookmarkBarFolderButtonCell> cell;
-  cell.reset([[BookmarkBarFolderButtonCell buttonCellForNode:nil
-                                                 contextMenu:nil
-                                                    cellText:nil
-                                                   cellImage:nil] retain]);
-  EXPECT_TRUE(cell);
-}
-
-} // namespace