#899 handlebars block helper multiple args fix

Before the fix the second select did not work. After the fix both selects are populated with identical options.

```javascript
Handlebars.registerHelper('range', function(from, to) {
    var accum = [];
    for(var i = from; i < to; i++)
        accum.push(i);
    return accum;
});

Handlebars.registerHelper('for', function(from, to, block) {
    var accum = '';
    for(var i = from; i < to; i++)
        accum += block.fn(i);
    return accum;
});
```

```html
<select name="year">
	{{#each range 1920 2013}}
		<option>{{this}}</option>
	{{/each}}
</select>

<select name="year">
	{{#for 1920 2013}}
		<option>{{this}}</option>
	{{/each}}
</select>
```