Test the genericity of Array.prototype.indexOf
Fix NaN/+0/-0 comparison in Array.prototype.indexOf
Fix NaN/+0/-0 comparison in Array.prototype.lastIndexOf
Add tests for Array.prototype.every
Add tests for Array.prototype.some
Add tests for Array.prototype.forEach
Add tests for Array.prototype.map
Fix inadvertent stringification in Array.prototype.concat
Fix placement of elements during Array.prototype.concat

Increase the index even if the element at the index does not exist
Fix off-by-one error with $' in String.prototype.replace
Fix special case in String.prototype.split
Fix String.prototype.indexOf to return the right index even with an offset
Fix String.prototype.lastIndexOf
Fix Number.prototype.toString(undefined)
Fix Number.prototype.toFixed to use ToString if exponent >= 21