Reviewed by Adam Barth.

        clean up python imports
        https://bugs.webkit.org/show_bug.cgi?id=53966

        Convert "import A.B.C.D as D" to "from A.B.C import D" and
        make some imports absolute as required by PEP-8

        * Scripts/webkitpy/common/checkout/scm.py:
        * Scripts/webkitpy/common/net/irc/ircbot.py:
        * Scripts/webkitpy/common/system/logutils.py:
        * Scripts/webkitpy/common/system/logutils_unittest.py:
        * Scripts/webkitpy/layout_tests/deduplicate_tests.py:
        * Scripts/webkitpy/layout_tests/port/chromium.py:
        * Scripts/webkitpy/layout_tests/port/mac.py: Remove some unused imports
        * Scripts/webkitpy/layout_tests/port/webkit.py:
        * Scripts/webkitpy/layout_tests/update_webgl_conformance_tests.py:
        * Scripts/webkitpy/tool/bot/irc_command.py:
        * Scripts/webkitpy/tool/bot/sheriffircbot.py:
        * Scripts/webkitpy/tool/commands/download.py:
        * Scripts/webkitpy/tool/commands/prettydiff.py:
        * Scripts/webkitpy/tool/commands/queries.py:
        * Scripts/webkitpy/tool/commands/roll.py:
        * Scripts/webkitpy/tool/commands/stepsequence.py:
        * Scripts/webkitpy/tool/commands/upload.py:
        * Scripts/webkitpy/tool/main.py:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@77913 268f45cc-cd09-0410-ab3c-d52691b4dbfc