Implement for..in for objects

[jcdickinson]

ECMASCript feature
I would like to see for..in syntax and execution implemented. ECMAScript specification. This is important for test262, as it uses for..in pretty extensively.

Example code

const myObject = {
 a: 'test1',
 b: 'test2'
};
let c = '';
for(const prop in myObject) {
 c += prop + '=' + myObject[prop] + ';';
}
c

The expected output is a=test1;b=test2;.

[tofpie]

Hi. Could I work on it?

[jcdickinson]

Hi. Could I work on it?

I have no objection. You might want to take a look at my closed PR to see if it applies to the subsequent changes.

If you have a WIP feel free to @ me, I'm somewhat familiar with the architecture.