Remove duplicate service workers "appcache" test

The upstream version of this test differs only in its improved "clean
up" logic. All "resource" files are identical.

BUG=688116, 410665
R=falken@chromium.org

Review-Url: https://codereview.chromium.org/2879643002
Cr-Commit-Position: refs/heads/master@{#471327}
5 files changed