Reviewed by Tony Chang.

        commit-queue should report port/platform information when commenting on flaky test bugs
        https://bugs.webkit.org/show_bug.cgi?id=50839

        This was a suggestion from Tony Chang this morning.
        I added a platform.py class so I could easily mock the platform call,
        but that may not be the final solution for this mocking.
        We'll try it and see.

        * Scripts/webkitpy/common/system/platform.py: Added.
        * Scripts/webkitpy/tool/bot/flakytestreporter.py:
        * Scripts/webkitpy/tool/bot/flakytestreporter_unittest.py:
        * Scripts/webkitpy/tool/commands/queues_unittest.py:
        * Scripts/webkitpy/tool/main.py:
        * Scripts/webkitpy/tool/mocktool.py:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@73798 268f45cc-cd09-0410-ab3c-d52691b4dbfc