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

tests/corelib/collection_removes_test.dart

Index: tests/corelib/collection_removes_test.dart
diff --git a/tests/corelib/collection_removes_test.dart b/tests/corelib/collection_removes_test.dart
index 738ce72f1f4c9cf9c0b637e1815b3f372d88e910..1914f6150655c9864ad6e76ad3ec462925bc5f24 100644
--- a/tests/corelib/collection_removes_test.dart
+++ b/tests/corelib/collection_removes_test.dart
@@ -86,16 +86,17 @@ void main() {
   ];
   for (var base in collections) {
     for (var delta in collections) {
-      testRemove(base.toList());
+      testRemove(base.toList(growable: true));
       testRemove(base.toSet());
 
       var deltaSet = delta.toSet();
-      testRemoveAll(base.toList(), delta);
-      testRemoveAll(base.toList(), deltaSet);
-      testRetainAll(base.toList(), delta);
-      testRetainAll(base.toList(), deltaSet);
-      testRemoveMatching(base.toList(), deltaSet.contains);
-      testRetainMatching(base.toList(), (e) => !deltaSet.contains(e));
+      testRemoveAll(base.toList(growable: true), delta);
+      testRemoveAll(base.toList(growable: true), deltaSet);
+      testRetainAll(base.toList(growable: true), delta);
+      testRetainAll(base.toList(growable: true), deltaSet);
+      testRemoveMatching(base.toList(growable: true), deltaSet.contains);
+      testRetainMatching(base.toList(growable: true),
+                         (e) => !deltaSet.contains(e));
 
       testRemoveAll(base.toSet(), delta);
       testRemoveAll(base.toSet(), deltaSet);