Method completion within a class doesn't work

Example code to reproduce a problem:

``` php
class foo {
    /**
     * @return DateTime
     */
    public function makeDateTime() {
    }

    public function __construct() {
        $dt = $this->makeDateTime();
        // $dt-> no completion
    }
}
```

Completion does work however outside class scope, e.g.:

``` php
$foo = new foo;
// $foo->makeDateTime()-> completion does work here
```
