Preserve alpha in WP_Image_Editor_GD when images are not resized.

Props joehoyle
see #23039


git-svn-id: http://core.svn.wordpress.org/trunk@23884 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Merge remote-tracking branch 'upstream/master'
Theme update
Add wp-config.php