Nested media queries using the "not" keyword should not be merged

Edited by @nex3

Specs: https://github.com/sass/sass-spec/pull/1267

• https://github.com/sass/dart-sass/pull/410
• https://github.com/sass/libsass/issues/2694

---

Nested media queries using the not keyword should not be merged. According to the spec, not flips the result for the entire query and does not apply to specific chunks.

For example:

@media (min-width: 500px) {
  @media not all and (min-width: 800px) {
    background: red;
  }
 }

Should compile to the same:

@media (min-width: 500px) {
  @media not all and (min-width: 800px) {
    background: red;
  }
 }

At 400px the background is expectedly not red.

Instead it compiles to:

@media not all and (min-width: 500px) and (min-width: 800px) {
  background: red;
}

At 400px the background is unexpectedly red.

[nex3]

This is a straightforward enough change that I don’t think it needs a full proposal. @xzyfer agreed?

[nex3]

Closing this out since LibSass is deprecated.