Re-use allocator in parser + lexer benchmarks.
I believe this is the recommended usage when parsing a bunch of files -
to re-use one allocator rather than create a fresh one for each run, so
it makes sense to me that this is what the benchmark should measure.
Doesn't show much difference on CodSpeed because it only runs the
benchmark once, and it treats allocations as free anyway. But I imagine
the difference may show up a bit more in a standard criterion benchmark.
6bc18e15e0