Index: src/wp-content/themes/twentyeleven/functions.php
===================================================================
--- src/wp-content/themes/twentyeleven/functions.php	(revision 45235)
+++ src/wp-content/themes/twentyeleven/functions.php	(working copy)
@@ -284,6 +284,9 @@
 
 		// Indicate widget sidebars can use selective refresh in the Customizer.
 		add_theme_support( 'customize-selective-refresh-widgets' );
+
+		// Use the new body-open hook introduced in WordPress 5.2
+		add_theme_support( 'body-open' );
 	}
 endif; // twentyeleven_setup
 
Index: src/wp-content/themes/twentyfifteen/functions.php
===================================================================
--- src/wp-content/themes/twentyfifteen/functions.php	(revision 45235)
+++ src/wp-content/themes/twentyfifteen/functions.php	(working copy)
@@ -165,6 +165,9 @@
 			)
 		);
 
+		// Add support for the body-open tag introduced in 5.2
+		add_theme_support( 'body-open' );
+
 		/*
 		 * This theme styles the visual editor to resemble the theme style,
 		 * specifically font, colors, icons, and column width.
Index: src/wp-content/themes/twentyfourteen/functions.php
===================================================================
--- src/wp-content/themes/twentyfourteen/functions.php	(revision 45235)
+++ src/wp-content/themes/twentyfourteen/functions.php	(working copy)
@@ -73,6 +73,9 @@
 		// Load regular editor styles into the new block-based editor.
 		add_theme_support( 'editor-styles' );
 
+		// Add support for the body-open tag introduced in 5.2
+		add_theme_support( 'body-open' );
+
 		// Load default block styles.
 		add_theme_support( 'wp-block-styles' );
 
Index: src/wp-content/themes/twentynineteen/functions.php
===================================================================
--- src/wp-content/themes/twentynineteen/functions.php	(revision 45235)
+++ src/wp-content/themes/twentynineteen/functions.php	(working copy)
@@ -37,6 +37,9 @@
 		// Add default posts and comments RSS feed links to head.
 		add_theme_support( 'automatic-feed-links' );
 
+		// Add support for the body-open tag introduced in 5.2
+		add_theme_support( 'body-open' );
+
 		/*
 		 * Let WordPress manage the document title.
 		 * By adding theme support, we declare that this theme does not use a
Index: src/wp-content/themes/twentyseventeen/functions.php
===================================================================
--- src/wp-content/themes/twentyseventeen/functions.php	(revision 45235)
+++ src/wp-content/themes/twentyseventeen/functions.php	(working copy)
@@ -36,6 +36,9 @@
 	// Add default posts and comments RSS feed links to head.
 	add_theme_support( 'automatic-feed-links' );
 
+	// Add support for the body-open tag introduced in 5.2
+	add_theme_support( 'body-open' );
+
 	/*
 	 * Let WordPress manage the document title.
 	 * By adding theme support, we declare that this theme does not use a
Index: src/wp-content/themes/twentysixteen/functions.php
===================================================================
--- src/wp-content/themes/twentysixteen/functions.php	(revision 45235)
+++ src/wp-content/themes/twentysixteen/functions.php	(working copy)
@@ -56,6 +56,9 @@
 		// Add default posts and comments RSS feed links to head.
 		add_theme_support( 'automatic-feed-links' );
 
+		// Add support for the body-open tag introduced in 5.2
+		add_theme_support( 'body-open' );
+
 		/*
 		 * Let WordPress manage the document title.
 		 * By adding theme support, we declare that this theme does not use a
Index: src/wp-content/themes/twentythirteen/functions.php
===================================================================
--- src/wp-content/themes/twentythirteen/functions.php	(revision 45235)
+++ src/wp-content/themes/twentythirteen/functions.php	(working copy)
@@ -80,6 +80,9 @@
 	// Load regular editor styles into the new block-based editor.
 	add_theme_support( 'editor-styles' );
 
+	// Add support for the body-open tag introduced in 5.2
+	add_theme_support( 'body-open' );
+
 	// Load default block styles.
 	add_theme_support( 'wp-block-styles' );
 
Index: src/wp-content/themes/twentytwelve/functions.php
===================================================================
--- src/wp-content/themes/twentytwelve/functions.php	(revision 45235)
+++ src/wp-content/themes/twentytwelve/functions.php	(working copy)
@@ -57,6 +57,9 @@
 	// This theme styles the visual editor with editor-style.css to match the theme style.
 	add_editor_style();
 
+	// Add support for the body-open tag introduced in 5.2
+	add_theme_support( 'body-open' );
+
 	// Load regular editor styles into the new block-based editor.
 	add_theme_support( 'editor-styles' );
 
Index: src/wp-includes/theme.php
===================================================================
--- src/wp-includes/theme.php	(revision 45235)
+++ src/wp-includes/theme.php	(working copy)
@@ -2327,6 +2327,7 @@
  * @since 5.0.0 The `responsive-embeds`, `align-wide`, `dark-editor-style`, `disable-custom-colors`,
  *              `disable-custom-font-sizes`, `editor-color-pallete`, `editor-font-sizes`,
  *              `editor-styles`, and `wp-block-styles` features were added.
+ * @since 5.2.0 The `body-open` feature was added.
  *
  * @global array $_wp_theme_features
  *
@@ -2333,7 +2334,7 @@
  * @param string $feature  The feature being added. Likely core values include 'post-formats',
  *                         'post-thumbnails', 'html5', 'custom-logo', 'custom-header-uploads',
  *                         'custom-header', 'custom-background', 'title-tag', 'starter-content',
- *                         'responsive-embeds', etc.
+ *                         'responsive-embeds', 'body-open' etc.
  * @param mixed  $args,... Optional extra arguments to pass along with certain features.
  * @return void|bool False on failure, void otherwise.
  */