fix: preserve empty lines between scss nested maps

Empty lines between SCSS maps nested within other maps are not being
preserved by prettier. This resolves that.

No issue was found for this particular bug. As a reference, it relates
to prettier#12536, which mentioned the issue via code comment and in the pull
request.

src/language-css/printer-postcss.js

@@ -918,7 +918,8 @@ function genericPrint(path, options, print) {
               path.map((childPath, index) => {
                 const child = childPath.getValue();
                 const isLast = index === node.groups.length - 1;
-                const printed = [print(), isLast ? "" : ","];
+
+                let printed = [print(), isLast ? "" : ","];
 
                 // Key/Value pair in open paren already indented
                 if (
@@ -931,17 +932,22 @@ function genericPrint(path, options, print) {
                 ) {
                   const parts = getDocParts(printed[0].contents.contents);
                   parts[1] = group(parts[1]);
-                  return group(dedent(printed));
+                  printed = [group(dedent(printed))];
                 }
 
                 if (
                   !isLast &&
                   child.type === "value-comma_group" &&
                   isNonEmptyArray(child.groups)
                 ) {
-                  const last = getLast(child.groups);
+                  let last = getLast(child.groups);
+
+                  // `value-paren_group` does not have location info, but its closing parenthesis does.
+                  if (!last.source && last.close) {
+                    last = last.close;
+                  }
+
                   if (
-                    // `value-paren_group` missing location info
                     last.source &&
                     isNextLineEmpty(options.originalText, last, locEnd)
                   ) {

tests/format/scss/parens/__snapshots__/jsfmt.spec.js.snap

@@ -28,6 +28,7 @@ $icons: (
     left: 253,
     top: 73,
   ),
+
   /* Should preserve empty lines */ cal-week-group:
     (
       left: 1,