Move fast/js/resources files to resources.

Move fast/js/resources/js-test-pre.js and
fast/js/resources/leak-check.js to the root resources
directory. They're used mostly by tests outside of fast/js.
Also, rename js-test-pre.js to js-test.js now that there's
no js-test-post.js.

TBR because it's impossible to review 6819 file changes in rietveld.

TBR=eae@chromium.org

Review URL: https://codereview.chromium.org/58533003

git-svn-id: svn://svn.chromium.org/blink/trunk@161296 bbb929c8-8fbe-4397-9dbb-9b2b20218538