/css/css-sizing/replaced-fractional-height-from-aspect-ratio.html isn't detected as a test

[gsnedders]

According to the manifest, this is a support file: it doesn't include testharness.js, and it doesn't have the filename required to be picked up as a manual test (i.e., -manual.html).

It's also the only test using check-layout.js (v. check-layout-th.js) in the tree; the non-testharness version should probably not exist because we don't support anything similar to WebKit or Blink's dumpAsText tests.

cc @bfgeek who wrote this test