Fix 3 tests using display: -webkit{-inline}?-grid

Those tests were forgotten when renaming the value so this
change just restores the testing to what it used to be.

Review URL: https://chromiumcodereview.appspot.com/23702053

git-svn-id: svn://svn.chromium.org/blink/trunk@158067 bbb929c8-8fbe-4397-9dbb-9b2b20218538