Extract PerfTest class from PerfTestRunner

Extract PerfTest class from PerfTestRunner
https://bugs.webkit.org/show_bug.cgi?id=83847

Reviewed by Hajime Morita.

Extracted PerfTest and ChromiumStylePerfTest from PerfTestRunner. This class abstracts a test
that was previously represented by a tuple.

Also moved the logic to determine whether a given test is chromium style or not from run() to
_collect_tests(). And moved the output parsing algorithms for parser style and chromium style
tests from PerfTestRunner to PerfTest and ChromiumStylePerfTest respectively so that we may
add new types of tests more easily.

* Scripts/webkitpy/performance_tests/perftest.py: Added.
(PerfTest):
(PerfTest.__init__):
(PerfTest.test_name):
(PerfTest.dirname):
(PerfTest.path_or_url):
(PerfTest._should_ignore_line_in_parser_test_result):
(PerfTest.parse_output):
(ChromiumStylePerfTest):
(ChromiumStylePerfTest.__init__):
(ChromiumStylePerfTest.parse_output):
* Scripts/webkitpy/performance_tests/perftestsrunner.py:
(PerfTestsRunner._collect_tests):
(PerfTestsRunner.run):
(PerfTestsRunner._run_tests_set):
(PerfTestsRunner._run_single_test):
* Scripts/webkitpy/performance_tests/perftestsrunner_unittest.py:
(run_test):
(_tests_for_runner):
(test_run_test_set_with_json_output):
(test_run_test_set_with_json_source):
(test_run_test_set_with_multiple_repositories):
(_collect_tests_and_sort_test_name):
(test_collect_tests):
(test_collect_tests_with_skipped_list):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@114076 268f45cc-cd09-0410-ab3c-d52691b4dbfc