"reload_style_on_change" would check if the target file is a symlink,
but only resolves the first link. If the symlink is acutally a chain of
symlink, such as what happens with NixOS's mkOutOfStoreSymlink, we will
not find the actual file style file.
Update the symlink resolution logic to walk down the symlink chain until
it finds a non-symlink. Also check against a the original filename
(which may be a symlink) to guard against infinitely looping on a
circular symlink chain.
