LibWeb: Implement AO transform_stream_unblock_write

Userland/Libraries/LibWeb/Streams/AbstractOperations.cpp

@@ -5175,6 +5175,14 @@ void transform_stream_set_up(TransformStream& stream, JS::NonnullGCPtr<Transform
     set_up_transform_stream_default_controller(stream, controller, transform_algorithm_wrapper, flush_algorithm_wrapper);
 }
 
+// https://streams.spec.whatwg.org/#transform-stream-unblock-write
+void transform_stream_unblock_write(TransformStream& stream)
+{
+    // 1. If stream.[[backpressure]] is true, perform ! TransformStreamSetBackpressure(stream, false).
+    if (stream.backpressure().has_value() && stream.backpressure().value())
+        transform_stream_set_backpressure(stream, false);
+}
+
 // https://streams.spec.whatwg.org/#is-non-negative-number
 bool is_non_negative_number(JS::Value value)
 {

Userland/Libraries/LibWeb/Streams/AbstractOperations.h

@@ -183,6 +183,7 @@ void transform_stream_error(TransformStream&, JS::Value error);
 void transform_stream_error_writable_and_unblock_write(TransformStream&, JS::Value error);
 void transform_stream_set_backpressure(TransformStream&, bool backpressure);
 void transform_stream_set_up(TransformStream&, JS::NonnullGCPtr<TransformAlgorithm>, JS::GCPtr<FlushAlgorithm> = {}, JS::GCPtr<CancelAlgorithm> = {});
+void transform_stream_unblock_write(TransformStream&);
 
 bool is_non_negative_number(JS::Value);
 bool can_transfer_array_buffer(JS::ArrayBuffer const& array_buffer);