| Index: Source/core/fileapi/Blob.idl | 
| diff --git a/Source/core/fileapi/Blob.idl b/Source/core/fileapi/Blob.idl | 
| index df6662d3af4987f83d8f87a467154ef0e6203360..dbc5e5acfc626d4b1e010007beeab995ccde92af 100644 | 
| --- a/Source/core/fileapi/Blob.idl | 
| +++ b/Source/core/fileapi/Blob.idl | 
| @@ -38,7 +38,7 @@ | 
| readonly attribute unsigned long long size; | 
| readonly attribute DOMString type; | 
|  | 
| -    [RaisesException] Blob slice(optional long long start, optional long long end, [TreatNullAs=NullString, TreatUndefinedAs=NullString] optional DOMString contentType); | 
| +    [RaisesException] Blob slice(optional long long start, optional long long end, [TreatUndefinedAs=NullString] optional DOMString? contentType); | 
| [RaisesException, CallWith=ExecutionContext, RuntimeEnabled=FileAPIBlobClose] void close(); | 
| }; | 
|  | 
|  |