webkit_unit_tests depends on webkit_test_support via content test support

It should depend on it directly.

BUG=none
R=mkwst@chromium.org

Review URL: https://codereview.chromium.org/105983004

git-svn-id: svn://svn.chromium.org/blink/trunk@164230 bbb929c8-8fbe-4397-9dbb-9b2b20218538