<===> input.scss
@import 'foo.css', "bar.css";

div {
  color: red;
}
<===> output.css
@import url(foo.css);
@import url(bar.css);
div {
  color: red;
}

<===> output-dart-sass.css
@import 'foo.css';
@import "bar.css";
div {
  color: red;
}