with() does not escape correctly

With this:

```php
return $this->mock('Kounta\MYOB\AccountRight\AccountRightClient')
            ->disableConstructor()
            ->expect('safeRequest')->with($requestUrl, 'POST', $data)
            ->done();
```

Generates invalid PHP code:

```php
if(json_encode(func_get_args()) == "[\"ABCD\/Contact\/\",\"POST\",\"{\\"foo\\":\\"bar\\"}\"]") {
```