[Pharo-project] Prune stack serialization

[Martin Dias]

Hi folks

In Fuel, we serialize a block closure with its state, including its
outerContext. This enables to serialize a sorted collection with its
sortBlock:

| bytes result |
bytes := FLSerializer serializeToByteArray: (SortedCollection sortBlock:
[:a :b | a > b ]).
result := FLMaterializer materializeFromByteArray: bytes.
result
addAll: #(1 2 3);
 yourself.
---> a SortedCollection(3 2 1)

Here the problem: the byte array is huge! (800kb) because we are
serializing unneeded context for the sort block.

We wonder how to prune it and save time and space.

Thanks in advance
Martín