Delete all the js-test-post-* files and rename the fast/js/mozilla js-test-* files.

The js-test-post-* files are not used. And the fast/js/mozilla copies
have diverged greatly. Better to rename them to avoid any confusion.

TBR=eae@chromium.org

Review URL: https://codereview.chromium.org/48343006

git-svn-id: svn://svn.chromium.org/blink/trunk@161289 bbb929c8-8fbe-4397-9dbb-9b2b20218538