LibWeb: Add a 'get a reader' helper method on ReadableStream

Author: https://github.com/shannonbooth
Commit: 9ce0c5914b
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3029
Reviewed-by: https://github.com/kennethmyhra ✅

Libraries/LibWeb/FileAPI/FileReader.cpp

@@ -134,7 +134,7 @@ WebIDL::ExceptionOr<void> FileReader::read_operation(Blob& blob, Type type, Opti
     auto stream = blob.get_stream();
 
     // 6. Let reader be the result of getting a reader from stream.
-    auto reader = TRY(acquire_readable_stream_default_reader(*stream));
+    auto reader = TRY(stream->get_a_reader());
 
     // 7. Let bytes be an empty byte sequence.
     ByteBuffer bytes;