a {
  background-image: -webkit-image-set(url(foo@1x.png) 1x, url(foo@2x.png) 2x);
  background-image: image-set(url(foo@1x.png) 1x, url(foo@2x.png) 2x);
}
h1 {
  background-image: -webkit-image-set(url("foo@1x.png") 1x, url("foo@2x.png") 2x);
  background-image: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}
.class {
  background-image: -webkit-image-set(url("foo@1x.png") 1x, url("foo@2x.png") 2x);
  background-image: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}
.class {
  border-image: -webkit-image-set(url("foo@1x.png") 1x, url("foo@2x.png") 2x);
  border-image: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}
.class {
  -webkit-mask: -webkit-image-set(url("foo@1x.png") 1x, url("foo@2x.png") 2x);
  mask: -webkit-image-set(url("foo@1x.png") 1x, url("foo@2x.png") 2x);
  mask: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}
.class {
  -webkit-mask-image: -webkit-image-set(url("foo@1x.png") 1x, url("foo@2x.png") 2x);
  mask-image: -webkit-image-set(url("foo@1x.png") 1x, url("foo@2x.png") 2x);
  mask-image: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}
.class {
  list-style: -webkit-image-set(url("foo@1x.png") 1x, url("foo@2x.png") 2x);
  list-style: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}
.class {
  list-style-image: -webkit-image-set(url("foo@1x.png") 1x, url("foo@2x.png") 2x);
  list-style-image: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}
.class {
  content: -webkit-image-set(url("foo@1x.png") 1x, url("foo@2x.png") 2x);
  content: image-set('foo@1x.png' 1x, "foo@2x.png" 2x);
}
.broken {
  content: -webkit-image-set(url("foo@1x.png") 1x, url("foo@2x.png") 2x) "test";
  content: image-set('foo@1x.png' 1x, "foo@2x.png" 2x) "test";
}
a {
  background-image: -webkit-image-set(url("foo@1x.png") 1x, url(foo@2x.png) 2x);
  background-image: image-set("foo@1x.png" 1x, url(foo@2x.png) 2x);
}
a {
  background-image: -webkit-image-set(url(foo@1x.png) 1x, unknown("foo@2x.png") 2x);
  background-image: image-set(url(foo@1x.png) 1x, unknown("foo@2x.png") 2x);
}