Remove unused layout test expected result

This was left for https://codereview.chromium.org/298703006/,
which removed the corresponding test HTML file.

BUG=355674
TEST=should not fail

Review URL: https://codereview.chromium.org/306433002

git-svn-id: svn://svn.chromium.org/blink/trunk@174805 bbb929c8-8fbe-4397-9dbb-9b2b20218538