<===> input.scss
@font-face { font-family:'foo';src:url(//foo.bar) format('woff2'); }
<===> output.css
@font-face {
  font-family: 'foo';
  src: url(//foo.bar) format("woff2");
}

<===> output-dart-sass.css
@font-face {
  font-family: "foo";
  src: url(//foo.bar) format("woff2");
}