methods of re-exported private items are not placed in the search index

E.g. take this crate:

``` rust
#[crate_id="test"];

pub use private::Foo;

mod private
{
    pub struct Foo;
    impl Foo
    {
        pub fn test_method() {}
    }
}
```

After generating the documentation with it, you cannot search for the `test_method` method. This can be manually verified by grepping for it in the `doc/test/search-index.js` file.
