assert: allow circular references

[Trott]

Checklist

• tests and code linting passes
• a test and/or benchmark is included
• the commit message follows commit guidelines

Affected core subsystem(s)

test assert

Description of change

assert.deepEqual() and assert.deepStrictEqual() will no longer throw a
RangeError if passed objects with circular references.

Refs: strager/node@56dbd80
Fixes: #6416

[Trott]

Er, nope, this won't work...all circular references are treated as identical, so this won't fire an AssertionError because c.b and b.b are both circular references, even though they are circular references to totally different things:

b = {};
b.a = 1;
b.b = b;

c = {};
c.a = 1;
c.b = c.a;

assert.deepStrictEqual(b, c);