Array.prototype.flat not accounted for

[tourdedave]

When running with eslint-plugin-node and specifying the following in package.json:

  "engines": {
    "node": ">=8.9.0"
  }

I expect the following to be flagged by no-unsupported-features/es-builtins since this feature was introduced in Node 11:

const a = [[0,1], [2,3]]
a.flat()

But it's not.

Is this a missing implementation in the ruleset or is reading a property on a variable like this not supported?