implement is()/not() instead of default truthy/falsy check
remove NaN class
replace Null::$null with Object::$null
fix broken proto chain with Object.prototype.*; allow apply without second arg; use better NaN check when might not be float; add tests
add array.concat
exception handler should special case for userland Error
update Object::$className; fix $error->getMessage
fix Object.prototype.toString; update tests
fix bug with String.prototype
implement strict mode
update tests
factor out runtime.php
optimize `a + b + c`
add tests
code style updates to codegen
update truthy handling `is()` to be less redundant
fix number handling to use to_number; add tests
update tests
remove comments during runtime build
x_new -> _new