Bug: own-of outside for-condition

>Choose one: is this a bug report or feature request?

This is likely a bug/oversight.

I apologize if this came up before. There's roughly 400 search results for `own of`.

[Demo](https://coffeescript.org/v2/#try:for%20own%20k%20of%20obj%0A%20%20do%20something%0A%20%20%0Aif%20own%20k%20of%20obj%0A%20%20do%20something%0A)

Currently `own k of obj` works differently from what I'd expect, which would be the same as it behaves inside a for-loop condition. Instead the `own` keyword is treated like a regular identifier.

### Input Code

```coffee
for own k of obj
do something

if own k of obj
do something

```

### Expected Behavior

```js
var k,
hasProp = {}.hasOwnProperty;

for (k in obj) {
if (!hasProp.call(obj, k)) continue;
something();
}

if(hasProp.call(obj, k)) {
something();
}
```
### Current Behavior

```js
var k,
hasProp = {}.hasOwnProperty;

for (k in obj) {
if (!hasProp.call(obj, k)) continue;
something();
}

if (own(k in obj)) {
something();
}
```
### Possible Solution

Change compilation output.

### Context

>How has this issue affected you?

Runtime errors.
### Environment

* CoffeeScript version: v2.3.2
* Node.js version: any

Start by compiling the reported CoffeeScript input containing `for own k of obj` and `if own k of obj`, then compare the output with the expected and current JavaScript shown in the issue. Trace how `own` is handled in a for-condition versus an ordinary conditional, and consider the issue complete when the conditional produces the expected own-property check without changing the existing loop behavior.

Written by the indexing model from the issue text.