webkitpy still imports simplejson

webkitpy still imports simplejson
https://bugs.webkit.org/show_bug.cgi?id=78161

Reviewed by Eric Seidel.

We no longer support Python 2.5, so we can rely upon Python's built-in
JSON package.

* Scripts/webkitpy/common/net/buildbot/buildbot.py:
* Scripts/webkitpy/common/net/resultsjsonparser.py:
* Scripts/webkitpy/layout_tests/controllers/test_expectations_editor.py:
* Scripts/webkitpy/layout_tests/layout_package/json_results_generator.py:
* Scripts/webkitpy/layout_tests/layout_package/json_results_generator_unittest.py:
* Scripts/webkitpy/layout_tests/models/test_expectations.py:
* Scripts/webkitpy/layout_tests/run_webkit_tests_integrationtest.py:
* Scripts/webkitpy/style/checkers/jsonchecker.py:
* Scripts/webkitpy/tool/servers/gardeningserver_unittest.py:
* Scripts/webkitpy/tool/servers/rebaselineserver_unittest.py:
* Scripts/webkitpy/tool/servers/reflectionhandler.py:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@107139 268f45cc-cd09-0410-ab3c-d52691b4dbfc