nrwt: clean up handling of 'expected' stats

nrwt: clean up handling of 'expected' stats
https://bugs.webkit.org/show_bug.cgi?id=92527

Reviewed by Tony Chang.

This patch alters the way we compute and log the "expected"
results and how we treat skipped tests; we will now log the
number of skipped tests separately from the categories, e.g.:

Found 31607 tests; running 24464.
Expect: 23496 passes   (23496 now,    0 wontfix)
Expect:   548 failures (  543 now,    5 wontfix)
Expect:   420 flaky    (  245 now,  175 wontfix)

(so that the "expect" totals add up to the "running" totals);
in addition, the totals in the one-line-progress reflect the
number of tests we will actually run. If --iterations or
--repeat-each are specified, the number of tests we run are
multiplied as appropriate, but the "expect" numbers are
unchanged, since we don't count multiple invocations of the same
test multiple times. In addition, if we are using --run-part or
--run-chunk, the tests we don't run are treated as skipped
for consistency. We will also log the values for --iterations
and --repeat each as part of the found/running line.

Previously the code had parsed and re-parsed the
TestExpectations files several times in an attempt to come up
with some sane statistics, but this was expensive and lead to
confusing layer; treating files as skipped in the way described
above is more consistent and cleaner.

* Scripts/webkitpy/layout_tests/controllers/manager.py:
(Manager._split_into_chunks_if_necessary):
(Manager.prepare_lists_and_print_output):
(Manager.run):
* Scripts/webkitpy/layout_tests/controllers/manager_unittest.py:
(ManagerTest.test_interrupt_if_at_failure_limits):
(ManagerTest.test_update_summary_with_result):
(ManagerTest.test_look_for_new_crash_logs):
(ResultSummaryTest.get_result_summary):
* Scripts/webkitpy/layout_tests/models/result_summary.py:
(ResultSummary.__init__):
* Scripts/webkitpy/layout_tests/models/test_expectations.py:
(TestExpectationParser.expectation_for_skipped_test):
(TestExpectations.__init__):
(TestExpectations.add_skipped_tests):
  Here we make add_skipped_tests() public, so that we can update
  the expectations for tests that we are skipping due to
  --run-part or --run-chunk; we use the wontfix flag so that
  the tests that are intentionally skipped aren't considered
  "fixable".
* Scripts/webkitpy/layout_tests/models/test_expectations_unittest.py:
(SkippedTests.check):
* Scripts/webkitpy/layout_tests/run_webkit_tests.py:
(parse_args):
* Scripts/webkitpy/layout_tests/views/printing.py:
(Printer.print_found):
(Printer):
(Printer.print_expected):
(Printer._print_result_summary):
(Printer._print_result_summary_entry):
  Here we split out printing the number of tests found and run
  from the expected results, to be clearer and so that we don't
  have to reparse the expectations to update the stats.
* Scripts/webkitpy/layout_tests/views/printing_unittest.py:
(Testprinter.get_result_summary):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@124116 268f45cc-cd09-0410-ab3c-d52691b4dbfc