run-pert-tests should have a --test-runner-count option
https://bugs.webkit.org/show_bug.cgi?id=111726

Reviewed by Ryosuke Niwa.

Add --test-runner-count option to run-perf-tests, with default value of 4.
This option allows command line configuration of the number of times to invoke
the test runner (serially, not in parallel) when running a specific test in
a test set.

* Scripts/webkitpy/performance_tests/perftest.py:
(PerfTest): Add DEFAULT_TEST_RUNNER_COUNT constant.
(PerfTest.__init__): Rename process_run_count to test_runner_count (throughout).
(PerfTest.run): Rename process_run_count to test_runner_count.
(SingleProcessPerfTest.__init__): Add test_runner_count optional argument.
(ChromiumStylePerfTest.__init__): Add test_runner_count optional argument.
(ReplayPerfTest.__init__): Add test_runner_count optional argument.
(PerfTestFactory.create_perf_test): Add test_runner_count optional argument.
* Scripts/webkitpy/performance_tests/perftestsrunner.py:
(PerfTestsRunner._parse_args): Add '--test-runner-count' option.
(PerfTestsRunner._collect_tests): Use test_runner_count when creating PerfTest.
* Scripts/webkitpy/performance_tests/perftestsrunner_integrationtest.py:
(MainTest._test_run_with_json_output): Add optional compare_logs argument.
(MainTest.test_run_with_repeat):
(MainTest.test_run_with_test_runner_count): Add new test for test-runner-count option semantics.
* Scripts/webkitpy/performance_tests/perftestsrunner_unittest.py:
(MainTest.test_default_args): Add test for default option argument values.
(MainTest.test_parse_args): Add test for test-runner-count option parsing.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@145173 268f45cc-cd09-0410-ab3c-d52691b4dbfc