Minor change - Rename autofill layout test file.

Rename input-autofilled.html to autofilled.html as the file now covers tests not only for <input> element.

R=tkent@chromium.org
BUG=Nobug

Review URL: https://codereview.chromium.org/479063003

git-svn-id: svn://svn.chromium.org/blink/trunk@180726 bbb929c8-8fbe-4397-9dbb-9b2b20218538