Enable the dialog for paste as plain text in the new TinyMCE paste plugin. Fixes #15278.

git-svn-id: https://develop.svn.wordpress.org/trunk@16133 602fd350-edb4-49c9-b593-d223f7449a82

wp-admin/includes/post.php

@@ -1470,6 +1470,7 @@ function wp_tiny_mce( $teeny = false, $settings = false ) {
 		'paste_remove_styles' => true,
 		'paste_remove_spans' => true,
 		'paste_strip_class_attributes' => 'all',
+		'paste_text_use_dialog' => true,
 		'wpeditimage_disable_captions' => $no_captions,
 		'plugins' => $plugins
 	);