Remove webkit_unit_tests_resources target.

As tested, webkit_unit_tests does not need it to run.

To test this, it was run the following command lines:

- Apply this patch.
$ rm -rf out/Debug
$ ./build/gyp_chromium
$ ninja -C out/Debug webkit_unit_tests
$ out/Debug/webkit_unit_tests

BUG=338338
TEST=see above
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/383233005

git-svn-id: svn://svn.chromium.org/blink/trunk@178016 bbb929c8-8fbe-4397-9dbb-9b2b20218538