check-webkit-style of the chromium test_expectations.txt file doesn't test all chromi...

check-webkit-style of the chromium test_expectations.txt file doesn't test all chromium ports
https://bugs.webkit.org/show_bug.cgi?id=76510

Reviewed by Adam Barth.

Unlike other style rules, if you get the syntax of the test_expectations.txt
file wrong, the layout tests won't run. Also, this check is simple and only
slows down committing if you actually modify one of the test_expectations.txt files.

* Scripts/webkitpy/style/checkers/test_expectations.py:
(TestExpectationsChecker.check_test_expectations):
(TestExpectationsChecker.check):
* Scripts/webkitpy/style/checkers/test_expectations_unittest.py:
(TestExpectationsTestCase.test_check_covers_all_configurations):
(TestExpectationsTestCase.test_check_covers_all_configurations.mock_check_test_expectations):
(TestExpectationsTestCase):
(assert_lines_lint):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@105452 268f45cc-cd09-0410-ab3c-d52691b4dbfc