Add support for new special number strings (#556)

See sass/sass#2584

CHANGELOG.md

@@ -1,3 +1,8 @@
+## 1.16.0
+
+* `rgb()` and `hsl()` now treat unquoted strings beginning with `env()`,
+  `min()`, and `max()` as special number strings like `calc()`.
+
 ## 1.15.3
 
 * Properly merge `all and` media queries. These queries were previously being

lib/src/value/string.dart

@@ -31,7 +31,7 @@ class SassString extends Value implements ext.SassString {
 
   bool get isSpecialNumber {
     if (hasQuotes) return false;
-    if (text.length < "calc(_)".length) return false;
+    if (text.length < "min(_)".length) return false;
 
     var first = text.codeUnitAt(0);
     if (equalsLetterIgnoreCase($c, first)) {
@@ -43,6 +43,21 @@ class SassString extends Value implements ext.SassString {
       if (!equalsLetterIgnoreCase($a, text.codeUnitAt(1))) return false;
       if (!equalsLetterIgnoreCase($r, text.codeUnitAt(2))) return false;
       return text.codeUnitAt(3) == $lparen;
+    } else if (equalsLetterIgnoreCase($e, first)) {
+      if (!equalsLetterIgnoreCase($n, text.codeUnitAt(1))) return false;
+      if (!equalsLetterIgnoreCase($v, text.codeUnitAt(2))) return false;
+      return text.codeUnitAt(3) == $lparen;
+    } else if (equalsLetterIgnoreCase($m, first)) {
+      var second = text.codeUnitAt(1);
+      if (equalsLetterIgnoreCase($a, second)) {
+        if (!equalsLetterIgnoreCase($x, text.codeUnitAt(2))) return false;
+        return text.codeUnitAt(3) == $lparen;
+      } else if (equalsLetterIgnoreCase($i, second)) {
+        if (!equalsLetterIgnoreCase($n, text.codeUnitAt(2))) return false;
+        return text.codeUnitAt(3) == $lparen;
+      } else {
+        return false;
+      }
     } else {
       return false;
     }

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.15.3
+version: 1.16.0-dev
 description: A Sass implementation in Dart.
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/sass/dart-sass