Fix for duplicating skin css files during minification. TINY-2810
Fix for duplicating skin css files during minification. TINY-2810

FernCreek/tinymce,FernCreek/tinymce,tinymce/tinymce,tinymce/tinymce,tinymce/tinymce,TeamupCom/tinymce,TeamupCom/tinymce,FernCreek/tinymce