Change new List(n) to return fixed length list.

tools/dom/src/CssClassSet.dart

Index: tools/dom/src/CssClassSet.dart
diff --git a/tools/dom/src/CssClassSet.dart b/tools/dom/src/CssClassSet.dart
index 51dd3b5663bd6043d29fcf75c9183205acb307f9..f4573ef5e511a1a3bfd18839a66ac6c7be9f4208 100644
--- a/tools/dom/src/CssClassSet.dart
+++ b/tools/dom/src/CssClassSet.dart
@@ -114,7 +114,8 @@ abstract class CssClassSet implements Set<String> {
   String get first => readClasses().first;
   String get last => readClasses().last;
   String get single => readClasses().single;
-  List<String> toList() => readClasses().toList();
+  List<String> toList({ bool growable: false }) =>
+      readClasses().toList(growable: growable);
   Set<String> toSet() => readClasses().toSet();
   String min([int compare(String a, String b)]) =>
       readClasses().min(compare);