util.types.isBigInt64Array and util.types.isBigUint64Array are in Node 10 but undocumented.

[jdalton]

util.types.isBigInt64Array and util.types.isBigUint64Array are in Node 10,
but are undocumented.

Related to #20016.

[targos]

Are they available without the --harmony-bigint flag?

[jdalton]

Are they available without the --harmony-bigint flag?

Yes, I believe there are no flags set in my setup.