REGRESSION (r160085): check-webkit-style: utf8' codec can't decode byte 0x89 in position 0: invalid start byte.
https://bugs.webkit.org/show_bug.cgi?id=126702

Patch by László Langó <llango.u-szeged@partner.samsung.com> on 2014-01-14
Reviewed by Alexey Proskuryakov.

Resolve regression and remove a FIXME comment that is already fixed.

* Scripts/webkitpy/common/system/filesystem.py:
(FileSystem.open_text_file_for_reading):
* Scripts/webkitpy/common/system/filesystem_unittest.py:
(RealFileSystemTest.test_read_and_write_file):
* Scripts/webkitpy/style/filereader.py:
(TextFileReader._read_lines):
* Scripts/webkitpy/style/filereader_unittest.py:
(TextFileReaderTest.test_count_delete_only_file):
(TextFileReaderTest):
(TextFileReaderTest.test_process_malformed_file):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@161986 268f45cc-cd09-0410-ab3c-d52691b4dbfc