This format matches against null bytes, and prevents the test
expectation from being interpreted as binary data.
bless_tests.php will automatically replace \0 with %0 as well.
The output normalization of bless_tests.php only detected absolute Unix
filenames; we extend this for absolute Windows filenames, regardless of
the platform we're running on (tests may have been run on Windows, but
bless_tests.php may be run from WSL or a Linux VM, for instance).
Resources used as array keys are generally handled by throwing a
notice and converting the resource to the resource handle. The only
exception is the [$resource => null] syntax, where this was treated
as an illegal offset type instead. However, this also only happened
for VM evaluations, the AST evaluator did handle resources correctly.
