comments don't respect whitespace control

i use handlebars to generate markdown, which is whitespace-sensitive.. so i use whitespace control a lot.. 

but it doesn't work on template comments.. at the moment, this command (note the trailing `~`): 

``` js
handlebars.compile("{{! comment ~}}      blah")();
```

returns this: 

``` js
'      blah'
```

whereas i expected this:

``` js
'blah'
```

should/could this be addressed?
