PostGetter::get_post_class unnecessarily instantiates return PostClass

[StuartFeldt]

Expected behavior

I expect the class wrapper for the returned post class in Timber::get_post to only be instantiated once.

Actual behavior

The class wrapper is instantiated twice.

Steps to reproduce behavior

Create a class wrapper which extends TimberPost, the constructor will be called twice.

What version of WordPress, PHP and Timber are you using?

WordPress 4.9.4, PHP PHP 7.0.27, Timber 1.7.0

How did you install Timber? (for example, from GitHub, Composer/Packagist, WP.org?)

Composer

[jarednova]

Closed by #1663 and #1661