PHP 8.1 changes the order of protected properties in the output
of serialize(). Previously they were at the end of the
serialized stream, now they are at the beginning.
Given that serialization formats have multiple equivalent encodings,
and there is no guarantee that they might not arbitrary change between
versions in backwards compatible ways, I think we should not do
byte for byte comparisons. Instead we should deserialize both
and compare the resulting objects for equality. This should test
what we want to know (That we can read serialized structures) well
also being safe against compatible format changes.
This fixes a number of failing ParserOutputTest::testSerialization
on php 8.1.
Bug: T313663
Change-Id: Ic7a08b436d65ab7492f343fa02281e245834aaea
e219728857