Themes: Use get_theme_file_path() in wp_theme_has_theme_json().

Ensure that all places where `theme.json` is included, use `get_theme_file_path` or `WP_Theme->get_file_path`, so that the path is run through `theme_file_path` filter. This change also means that the method `get_file_path_from_theme` can be deprecated, as it is no longer used in core. 

Props flixos90, spacedmonkey, costdev, johnbillion, oglekler, hellofromtonya, mukesh27, audrasjb, oandregal.
Fixes #57629.

git-svn-id: https://develop.svn.wordpress.org/trunk@56073 602fd350-edb4-49c9-b593-d223f7449a82

Author: spacedmonkey

src/wp-includes/class-wp-theme-json-resolver.php

@@ -238,9 +238,9 @@ public static function get_theme_data( $deprecated = array(), $options = array()
 		$options = wp_parse_args( $options, array( 'with_supports' => true ) );
 
 		if ( null === static::$theme || ! static::has_same_registered_blocks( 'theme' ) ) {
-			$theme_json_file = static::get_file_path_from_theme( 'theme.json' );
 			$wp_theme        = wp_get_theme();
-			if ( '' !== $theme_json_file ) {
+			$theme_json_file = $wp_theme->get_file_path( 'theme.json' );
+			if ( is_readable( $theme_json_file ) ) {
 				$theme_json_data = static::read_json_file( $theme_json_file );
 				$theme_json_data = static::translate( $theme_json_data, $wp_theme->get( 'TextDomain' ) );
 			} else {
@@ -260,8 +260,8 @@ public static function get_theme_data( $deprecated = array(), $options = array()
 
 			if ( $wp_theme->parent() ) {
 				// Get parent theme.json.
-				$parent_theme_json_file = static::get_file_path_from_theme( 'theme.json', true );
-				if ( '' !== $parent_theme_json_file ) {
+				$parent_theme_json_file = $wp_theme->parent()->get_file_path( 'theme.json' );
+				if ( $theme_json_file !== $parent_theme_json_file && is_readable( $parent_theme_json_file ) ) {
 					$parent_theme_json_data = static::read_json_file( $parent_theme_json_file );
 					$parent_theme_json_data = static::translate( $parent_theme_json_data, $wp_theme->parent()->get( 'TextDomain' ) );
 					$parent_theme           = new WP_Theme_JSON( $parent_theme_json_data );

src/wp-includes/global-styles-and-settings.php

@@ -408,12 +408,7 @@ function wp_theme_has_theme_json() {
 	}
 
 	// Does the theme have its own theme.json?
-	$theme_has_support = is_readable( get_stylesheet_directory() . '/theme.json' );
-
-	// Look up the parent if the child does not have a theme.json.
-	if ( ! $theme_has_support ) {
-		$theme_has_support = is_readable( get_template_directory() . '/theme.json' );
-	}
+	$theme_has_support = is_readable( get_theme_file_path( 'theme.json' ) );
 
 	return $theme_has_support;
 }