Not insert unnecessary blank line.

Our test files are structured as follows.

```js
/**
 * @fileoverview Unit test for my.app.SomeClass.
 */
goog.require('my.app.SomeClass');


describe('my.app.SomeClass', function() {
  // ...
});
```

In this case, fixclosure inserts a blank line between fileoverview JSDoc and `goog.require()`.