| Index: tool/input_sdk/patch/internal_patch.dart | 
| diff --git a/tool/input_sdk/patch/internal_patch.dart b/tool/input_sdk/patch/internal_patch.dart | 
| index 16afd5f3aa6332ec62190bdf31b5ff3455f4f898..f5bce774f35fbb72748a630b3e7d085a717f5372 100644 | 
| --- a/tool/input_sdk/patch/internal_patch.dart | 
| +++ b/tool/input_sdk/patch/internal_patch.dart | 
| @@ -23,3 +23,9 @@ List makeListFixedLength(List growableList) { | 
| JSArray.markFixedList(growableList); | 
| return growableList; | 
| } | 
| + | 
| +@patch | 
| +List makeFixedListUnmodifiable(List list) { | 
| +  JSArray.markUnmodifiableList(list); | 
| +  return list; | 
| +} | 
|  |