documentcloud/underscore — pull request #1037 by varfunction (2013-03-28 09:25:06+00:00)
Title: use isArray or +length？

When I read the source file, I found that if i write code as follow, it will not correct.
```js
var obj = {
'heght': 2,
'width': 3,
'length': 4
};
var result = _.size(obj);
```
the size() function is:
```js
// Return the number of elements in an object.
_.size = function(obj) {
if (obj == null) return 0;
return (obj.length === +obj.length) ? obj.length : _.keys(obj).length;
};
```

so, i think maybe this is a better way, isn't it?
```js
// Return the number of elements in an object.
_.size = function(obj) {
if (obj == null) return 0;
return _.isArray(obj) ? obj.length : _.keys(obj).length;
};
```