should_proceed_with_work_item is unused and can be removed

should_proceed_with_work_item is unused and can be removed
https://bugs.webkit.org/show_bug.cgi?id=79416

Reviewed by Eric Seidel.

We used to use this function to check whether the tree is red.  Now, we
don't use external measures of whether to proceed with work items.
Instead, we analyze them with the idea in mind that the tree might be
red.

* Scripts/webkitpy/tool/bot/queueengine.py:
(QueueEngineDelegate.next_work_item):
(QueueEngine.run):
* Scripts/webkitpy/tool/bot/queueengine_unittest.py:
(LoggingDelegate):
(LoggingDelegate.next_work_item):
(RaisingDelegate.process_work_item):
(QueueEngineTest.test_terminating_error):
* Scripts/webkitpy/tool/commands/earlywarningsystem.py:
(AbstractEarlyWarningSystem.__init__):
* Scripts/webkitpy/tool/commands/queues.py:
(AbstractQueue.next_work_item):
(FeederQueue.next_work_item):
(CommitQueue.next_work_item):
(AbstractReviewQueue.next_work_item):
(StyleQueue.__init__):
* Scripts/webkitpy/tool/commands/queues_unittest.py:
(FeederQueueTest.test_feeder_queue):
(CommitQueueTest.test_commit_queue):
(test_commit_queue_failure):
(test_commit_queue_failure_with_failing_tests):
(test_rollout):
(test_rollout_lands):
(StyleQueueTest.test_style_queue_with_style_exception):
(test_style_queue_with_watch_list_exception):
* Scripts/webkitpy/tool/commands/queuestest.py:
(QueuesTest.assert_queue_outputs):
* Scripts/webkitpy/tool/commands/sheriffbot.py:
(SheriffBot.next_work_item):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@108737 268f45cc-cd09-0410-ab3c-d52691b4dbfc