`assert.deepEqual` treats RegExp literals equal to `{}`

[hirokith]

Just as the title says,

~ ➤ n io use 1.6.4                                                                            
> assert.deepEqual(/a/, {})
undefined

expect AssertionError.

[bnoordhuis]

That was fixed by the introduction of assert.deepStrictEqual() in #639. People felt that modifying assert.deepEqual() would lead to too much fallout.