diff -r 490d5cc509ed -r cf61fcea0001 wp/wp-includes/functions.wp-styles.php
--- a/wp/wp-includes/functions.wp-styles.php	Tue Jun 09 11:14:17 2015 +0000
+++ b/wp/wp-includes/functions.wp-styles.php	Mon Oct 14 17:39:30 2019 +0200
@@ -1,11 +1,11 @@
 <?php
 /**
- * BackPress Styles Procedural API
+ * Dependencies API: Styles functions
  *
  * @since 2.6.0
  *
  * @package WordPress
- * @subpackage BackPress
+ * @subpackage Dependencies
  */
 
 /**
@@ -76,7 +76,7 @@
  *
  * @since 3.3.0
  *
- * @param string $handle Name of the stylesheet to add the extra styles to. Must be lowercase.
+ * @param string $handle Name of the stylesheet to add the extra styles to.
  * @param string $data   String containing the CSS styles to be added.
  * @return bool True on success, false on failure.
  */
@@ -84,7 +84,12 @@
 	_wp_scripts_maybe_doing_it_wrong( __FUNCTION__ );
 
 	if ( false !== stripos( $data, '</style>' ) ) {
-		_doing_it_wrong( __FUNCTION__, __( 'Do not pass style tags to wp_add_inline_style().' ), '3.7' );
+		_doing_it_wrong( __FUNCTION__, sprintf(
+			/* translators: 1: <style>, 2: wp_add_inline_style() */
+			__( 'Do not pass %1$s tags to %2$s.' ),
+			'<code>&lt;style&gt;</code>',
+			'<code>wp_add_inline_style()</code>'
+		), '3.7.0' );
 		$data = trim( preg_replace( '#<style[^>]*>(.*)</style>#is', '$1', $data ) );
 	}
 
@@ -95,23 +100,27 @@
  * Register a CSS stylesheet.
  *
  * @see WP_Dependencies::add()
- * @link http://www.w3.org/TR/CSS2/media.html#media-types List of CSS media types.
+ * @link https://www.w3.org/TR/CSS2/media.html#media-types List of CSS media types.
  *
  * @since 2.6.0
+ * @since 4.3.0 A return value was added.
  *
- * @param string      $handle Name of the stylesheet.
- * @param string|bool $src    Path to the stylesheet from the WordPress root directory. Example: '/css/mystyle.css'.
- * @param array       $deps   An array of registered style handles this stylesheet depends on. Default empty array.
- * @param string|bool $ver    String specifying the stylesheet version number. Used to ensure that the correct version
- *                            is sent to the client regardless of caching. Default 'false'. Accepts 'false', 'null', or 'string'.
- * @param string      $media  Optional. The media for which this stylesheet has been defined.
- *                            Default 'all'. Accepts 'all', 'aural', 'braille', 'handheld', 'projection', 'print',
- *                            'screen', 'tty', or 'tv'.
+ * @param string           $handle Name of the stylesheet. Should be unique.
+ * @param string           $src    Full URL of the stylesheet, or path of the stylesheet relative to the WordPress root directory.
+ * @param array            $deps   Optional. An array of registered stylesheet handles this stylesheet depends on. Default empty array.
+ * @param string|bool|null $ver    Optional. String specifying stylesheet version number, if it has one, which is added to the URL
+ *                                 as a query string for cache busting purposes. If version is set to false, a version
+ *                                 number is automatically added equal to current installed WordPress version.
+ *                                 If set to null, no version is added.
+ * @param string           $media  Optional. The media for which this stylesheet has been defined.
+ *                                 Default 'all'. Accepts media types like 'all', 'print' and 'screen', or media queries like
+ *                                 '(orientation: portrait)' and '(max-width: 640px)'.
+ * @return bool Whether the style has been registered. True on success, false on failure.
  */
 function wp_register_style( $handle, $src, $deps = array(), $ver = false, $media = 'all' ) {
 	_wp_scripts_maybe_doing_it_wrong( __FUNCTION__ );
 
-	wp_styles()->add( $handle, $src, $deps, $ver, $media );
+	return wp_styles()->add( $handle, $src, $deps, $ver, $media );
 }
 
 /**
@@ -134,23 +143,25 @@
  *
  * Registers the style if source provided (does NOT overwrite) and enqueues.
  *
- * @see WP_Dependencies::add(), WP_Dependencies::enqueue()
- * @link http://www.w3.org/TR/CSS2/media.html#media-types List of CSS media types.
+ * @see WP_Dependencies::add()
+ * @see WP_Dependencies::enqueue()
+ * @link https://www.w3.org/TR/CSS2/media.html#media-types List of CSS media types.
  *
  * @since 2.6.0
  *
- * @param string      $handle Name of the stylesheet.
- * @param string|bool $src    Path to the stylesheet from the root directory of WordPress. Example: '/css/mystyle.css'.
- * @param array       $deps   An array of registered style handles this stylesheet depends on. Default empty array.
- * @param string|bool $ver    String specifying the stylesheet version number, if it has one. This parameter is used
- *                            to ensure that the correct version is sent to the client regardless of caching, and so
- *                            should be included if a version number is available and makes sense for the stylesheet.
- * @param string      $media  Optional. The media for which this stylesheet has been defined.
- *                            Default 'all'. Accepts 'all', 'aural', 'braille', 'handheld', 'projection', 'print',
- *                            'screen', 'tty', or 'tv'.
+ * @param string           $handle Name of the stylesheet. Should be unique.
+ * @param string           $src    Full URL of the stylesheet, or path of the stylesheet relative to the WordPress root directory.
+ *                                 Default empty.
+ * @param array            $deps   Optional. An array of registered stylesheet handles this stylesheet depends on. Default empty array.
+ * @param string|bool|null $ver    Optional. String specifying stylesheet version number, if it has one, which is added to the URL
+ *                                 as a query string for cache busting purposes. If version is set to false, a version
+ *                                 number is automatically added equal to current installed WordPress version.
+ *                                 If set to null, no version is added.
+ * @param string           $media  Optional. The media for which this stylesheet has been defined.
+ *                                 Default 'all'. Accepts media types like 'all', 'print' and 'screen', or media queries like
+ *                                 '(orientation: portrait)' and '(max-width: 640px)'.
  */
-function wp_enqueue_style( $handle, $src = false, $deps = array(), $ver = false, $media = 'all' ) {
-	global $wp_styles;
+function wp_enqueue_style( $handle, $src = '', $deps = array(), $ver = false, $media = 'all' ) {
 	_wp_scripts_maybe_doing_it_wrong( __FUNCTION__ );
 
 	$wp_styles = wp_styles();
@@ -180,8 +191,6 @@
 /**
  * Check whether a CSS stylesheet has been added to the queue.
  *
- * @global WP_Styles $wp_styles The WP_Styles object for printing styles.
- *
  * @since 2.8.0
  *
  * @param string $handle Name of the stylesheet.