Properly handle trailing commas combined with newlines

src/selector.rs

@@ -57,7 +57,10 @@ impl Display for Selector {
                     while let Some(sel) = iter.peek() {
                         if sel != &&SelectorKind::Multiple {
                             write!(f, ",")?;
-                            if sel != &&SelectorKind::Newline {
+                            if sel == &&SelectorKind::Newline {
+                                iter.next();
+                                f.write_char('\n')?;
+                            } else {
                                 f.write_char(' ')?;
                             }
                             break;
@@ -65,6 +68,15 @@ impl Display for Selector {
                         iter.next();
                         devour_whitespace(&mut iter);
                     }
+                    while let Some(sel) = iter.peek() {
+                        if sel != &&SelectorKind::Multiple
+                            && sel != &&SelectorKind::Newline
+                            && !sel.is_whitespace()
+                        {
+                            break;
+                        }
+                        iter.next();
+                    }
                 }
                 _ => write!(f, "{}", s)?,
             }

tests/selectors.rs

@@ -261,3 +261,8 @@ test!(
     "a,\nb {\n  c {\n    color: blue;\n  }\n  color: red;\n}\n",
     "a,\nb {\n  color: red;\n}\na c,\nb c {\n  color: blue;\n}\n"
 );
+test!(
+    trailing_comma_newline,
+    "#foo #bar,,\n,#baz #boom, {a: b}",
+    "#foo #bar,\n#baz #boom {\n  a: b;\n}\n"
+);