Example for things like isString():

• Object.create(String.prototype)
• new String()
• new class extends String {}
• new iframe.contentWindow.String()
• { [Symbol.toStringTag]: "String" }
• new class String {}
• new class String { [Symbol.toStringTag] = "String" }
• new (iframe.contentWindow.eval("class String { [Symbol.toStringTag] = 'String' }"))()

@mesqueeb Thoughts on what each of these edge-cases should return?