add skia_test_expectations override file to chromium NRWT

add skia_test_expectations override file to chromium NRWT
https://bugs.webkit.org/show_bug.cgi?id=86749

Reviewed by Dirk Pranke

* Scripts/webkitpy/layout_tests/port/base.py:
(Port.test_expectations_overrides):
* Scripts/webkitpy/layout_tests/port/chromium.py:
(ChromiumPort.test_expectations_overrides):
* Scripts/webkitpy/layout_tests/port/chromium_unittest.py:
(ChromiumPortTest.test_overrides_and_builder_names):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@117789 268f45cc-cd09-0410-ab3c-d52691b4dbfc