\Magento\Framework\Image\Adapter\Gd2::_createEmptyImage() does not free the previous GD image resource _imageHandler with imagedestroy before creating a new one

[dmitrii-fediuk]

https://mage2.pro/t/292

Similar to #2694

[mazhalai]

@dfediuk thank you! We have created ticket MAGETWO-46918 to fix this.

[mazhalai]

This issue has been fixed in the develop branch. Closing ticket.