Status code is ignored when body is missing from response code (Node JS runtime)

I'm running functions in the Node JS runtime. When returning a response object with status code but without `body` the status code will be ignored and will always return 200.

The following example will return 500 as expected (`body` is passed in the response):
```
module.exports = function (context, req) {
context.res = {
status: 500,
body: "error"
};
context.done();
};
```

So is the following, where response isn't considered an object:
```
module.exports = function (context, req) {
context.res.status = 500;
context.done();
};
```

However, the following example will return **200**:
```
module.exports = function (context, req) {
context.res = {
status: 500
};
context.done();
};
```

Seems like the issue in the following implementation, where it expects to have a `body` property when response is passed as an object: https://github.com/Azure/azure-functions-host/blob/43ad9216b88b4c5329190ff56fad0980641883de/src/WebJobs.Script/Binding/Http/HttpBinding.cs#L104

Thanks,
Benny

Start at src/WebJobs.Script/Binding/Http/HttpBinding.cs around line 104, as linked in the issue, and reproduce the three Node.js response examples. Compare how an object with status but no body is handled; the work is done when that response preserves status 500 instead of returning 200.

Written by the indexing model from the issue text.