Some minor check-webkit-style code clean-ups. This revision

Some minor check-webkit-style code clean-ups.  This revision
contains no new functionality.

Reviewed by Shinichiro Hamaji.

https://bugs.webkit.org/show_bug.cgi?id=34932

* Scripts/check-webkit-style:
  - Replaced the call to webkit_argument_defaults() with a
    default parameter in the ArgumentParser constructor.

* Scripts/webkitpy/style/checker.py:
  - Removed the WEBKIT prefix from the default global variables.
  - Prefixed several of the global variables with an underscore
    to reflect that they are used internally.
  - Renamed _DEFAULT_FILTER_RULES to _BASE_FILTER_RULES.
  - Addressed a FIXME by changing the _PATH_RULES_SPECIFIER
    configuration from list-tuple pairs to list-list pairs.
  - Renamed style_categories() to _all_categories().
  - Renamed webkit_argument_defaults() to _check_webkit_style_defaults().
  - Renamed the ArgumentDefaults class to DefaultCommandOptionValues.
  - In the ArgumentParser class--
    - Renamed the doc_print attribute to stderr_write.
    - Other minor updates.

* Scripts/webkitpy/style/checker_unittest.py:
  - Updated the import statements and unit test classes as necessary.
  - Added assertions to test _PATH_RULES_SPECIFIER more fully.

* Scripts/webkitpy/style/error_handlers_unittest.py:
  - Updated the unit test classes as necessary.
  - Changed StyleErrorHandlerTestBase to store a list of error
    messages rather than just the last one.

* Scripts/webkitpy/style/filter.py:
  - Altered FilterConfiguration._path_rules_from_path()
    to convert the path_rules list to a tuple.

* Scripts/webkitpy/style/filter_unittest.py:
  - Updated the unit tests to reflect the change from tuples to
    lists in the _PATH_RULES_SPECIFIER configuration variable.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@54874 268f45cc-cd09-0410-ab3c-d52691b4dbfc