Function create_isolate_create_params 

pub fn create_isolate_create_params<TSys: DenoLibSys>(
    sys: &TSys,
) -> Option<CreateParams>

By default V8 uses 1.4Gb heap limit which is meant for browser tabs. Instead probe for the total memory on the system and use it instead as a default. In case the platform is Linux and DENO_USE_CGROUPS is set, parse cgroup config to get the cgroup-constrained memory limit.