Index: theme.php
===================================================================
--- theme.php	(revision 29298)
+++ theme.php	(working copy)
@@ -1412,6 +1412,20 @@
  * @return array If registered, a list of editor stylesheet URLs.
  */
 function get_editor_stylesheets() {
+	/**
+	 * Filter editor stylesheets output.
+	 *
+	 * If the filtered output isn't empty, it will be used instead of generating the stylesheets.
+	 *
+	 * @since 4.0.0
+	 *
+	 * @param array $array Empty variable to be replaced with stylesheets array.
+	 */
+	$override = apply_filters( 'get_editor_stylesheets_override', array() );
+	if ( ! empty( $override ) ) {
+		return $override;
+	}
+
 	$stylesheets = array();
 	// load editor_style.css if the current theme supports it
 	if ( ! empty( $GLOBALS['editor_styles'] ) && is_array( $GLOBALS['editor_styles'] ) ) {
@@ -1447,7 +1461,15 @@
 			}
 		}
 	}
-	return $stylesheets;
+
+	/**
+	 * Filter editor stylesheets output.
+	 *
+	 * @since 4.0.0
+	 *
+	 * @param array $stylesheets Stylesheets array output.
+	 */
+	return apply_filters( 'get_editor_stylesheets', $stylesheets );
 }
 
 /**