array/object comparison is not symmetric

[davidje13]

Due to the way Arrays are identified, it is possible to construct an object which "looks like" an array, but only when passed as the second argument:

const v1 = ['a', 'b'];
const v2 = { 0: 'a', 1: 'b', 2: 'c', length: 2, constructor: Array };
equal(v1, v2); // = true
equal(v2, v1); // = false

It doesn't seem particularly problematic or risky either way, but the asymmetry of the arguments is surprising.

There is also a similar (related?) issue that any extra properties on an array are not checked:

const v1 = Object.assign(['a', 'b'], { woo: 'hi' });
const v2 = ['a', 'b'];
equal(v1, v2); // = true
equal(v2, v1); // = true

Both of these behaviours diverge from the behaviour of util.isDeepStrictEqual