serialize
Serializes the @node for later deserialization via gsk_render_node_deserialize(). No guarantees are made about the format used other than that the same version of GTK will be able to deserialize the result of a call to gsk_render_node_serialize() and gsk_render_node_deserialize() will correctly reject files it cannot open that were created with previous versions of GTK.
The intended use of this functions is testing, benchmarking and debugging. The format is not meant as a permanent storage format.
Return
a GBytes
representing the node.