This became possible with brotli 1.2.0

It is my understanding pre-this change there was basically no
enforced limit on the amount of bytes "coming out" of
decompressor.process(); in other words: chunk size did not
apply to the most relevant (potentially blowing up) part of
the equation.

We had a MaxDataReader in place, but that would come "too late"
since all the mem-consuming stuff would happen right in brotli_generator
before any limiting would be possible.

See google/brotli#1381