More edge-case tests

[jcbhmr]

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?

[mesqueeb]

this is literally all JavaScript i've never used in my life so I don't really know or care too much tbh XD

Whatever you think is best is probably OK. I have no strong feelings as I use pretty basic JavaScript syntax in my code. Readability ftw.