Function for rendering images should fill the image and the tile buffer with black color to resolve graphical artifacts with images with transparent background.

Function for rendering images should fill the image and the tile buffer with black color to resolve graphical artifacts with images with transparent background.

Issues:
https://github.com/ariya/phantomjs/issues/11276
https://github.com/ariya/phantomjs/issues/11007
https://github.com/ariya/phantomjs/issues/11366