Object.getOwnPropertyNames/getOwnPropertyDescriptor/getOwnPropertyDescriptors/for-of loop not working with NativeJavaXxxx stuff

[p-bakker]

=>Object.getOwnPropertyNames(java.math.BigInteger)
org.mozilla.javascript.EcmaError: TypeError: Expected argument of type object, but instead had type function (internal_anon#1)

=>Object.getOwnPropertyDescriptor(java.math.BigInteger, 'valueOf')
org.mozilla.javascript.EcmaError: TypeError: Expected argument of type object, but instead had type function (internal_anon#1)

=>for (var x of java.math.BigInteger) console.log(x)
org.mozilla.javascript.EcmaError: TypeError: [JavaClass java.math.BigInteger] is not iterable (internal_anon#1)

[tuchida]

// * NativeJavaClass
Object.getOwnPropertyNames(java.math.BigInteger)
// js: uncaught JavaScript runtime exception: TypeError: Expected argument of type object, but instead had type function
// 	at (unknown):2

// * NativeJavaObject
Object.getOwnPropertyNames(java.math.BigInteger.valueOf(0))
// js: uncaught JavaScript runtime exception: TypeError: Expected argument of type object, but instead had type object
// 	at (unknown):3

// * NativeJavaPackage
Object.getOwnPropertyNames(java.math)
// BigInteger
// 
// <- laoded Only?

// * NativeJavaMap
Object.getOwnPropertyNames(new java.util.HashMap({ a: 1 }))
// js: uncaught JavaScript runtime exception: TypeError: Expected argument of type object, but instead had type object
// 	at (unknown):3
//
// <- Is it 'a' to expect? or methods?

// * java.lang.String
Object.getOwnPropertyNames(java.lang.String.valueOf('abc'))
// js: uncaught JavaScript runtime exception: TypeError: Expected argument of type object, but instead had type object
// 	at (unknown):7

> =>for (var x of java.math.BigInteger) console.log(x)
> org.mozilla.javascript.EcmaError: TypeError: [JavaClass java.math.BigInteger] is not iterable (internal_anon#1)

I don't see a problem with NativeJavaClass being non-iterative. NativeJavaObject that I want to make iterable were supported by #846.

[tonygermano]

I independently found this problem and mentioned it in #1615 (comment). The main problem is that Object.getOwnPropertyNames (and many other static methods on the built-in Object) requires the object being acted upon to be an instance of ScriptableObject, while most of the NativeJavaXxxx classes do not extend ScriptableObject.

I believe this is incorrect, as ScriptableObject is only supposed to be a reference implementation. However, our current interfaces do not really allow for correct implementations.