I18N: Use correct default value for JavaScript translations path.

The `$path` parameter of some script translation functions had a default value of `null`, even though the parameter is documented as a string.

This commit corrects the default value for `$path` in:
* `WP_Dependency::set_translations()`
* `WP_Scripts::set_translations()`
* `wp_set_script_translations()`

Additionally, this commit removes an `is_string()` check for `$path` in `load_script_textdomain()`. Now that the default value for `$path` in that function has also been corrected to an empty string instead of `null`, that check is no longer necessary, as it would ''hide'' an error which should be ''fixed'' (at the source of the problem) instead.

Follow-up to [54349].

Props jrf, johnjamesjacoby.
See #55967, #55656.

git-svn-id: https://develop.svn.wordpress.org/trunk@54351 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-includes/class-wp-dependency.php

@@ -126,7 +126,7 @@ public function add_data( $name, $data ) {
 	 * @param string $path   Optional. The full file path to the directory containing translation files.
 	 * @return bool False if $domain is not a string, true otherwise.
 	 */
-	public function set_translations( $domain, $path = null ) {
+	public function set_translations( $domain, $path = '' ) {
 		if ( ! is_string( $domain ) ) {
 			return false;
 		}

src/wp-includes/class-wp-scripts.php

@@ -573,7 +573,7 @@ public function set_group( $handle, $recursion, $group = false ) {
 	 * @param string $path   Optional. The full file path to the directory containing translation files.
 	 * @return bool True if the text domain was registered, false if not.
 	 */
-	public function set_translations( $handle, $domain = 'default', $path = null ) {
+	public function set_translations( $handle, $domain = 'default', $path = '' ) {
 		if ( ! isset( $this->registered[ $handle ] ) ) {
 			return false;
 		}
@@ -605,7 +605,11 @@ public function print_translations( $handle, $display = true ) {
 		}
 
 		$domain = $this->registered[ $handle ]->textdomain;
-		$path   = $this->registered[ $handle ]->translations_path;
+		$path   = '';
+
+		if ( isset( $this->registered[ $handle ]->translations_path ) ) {
+			$path = $this->registered[ $handle ]->translations_path;
+		}
 
 		$json_translations = load_script_textdomain( $handle, $domain, $path );
 

src/wp-includes/functions.wp-scripts.php

@@ -237,7 +237,7 @@ function wp_localize_script( $handle, $object_name, $l10n ) {
  * @param string $path   Optional. The full file path to the directory containing translation files.
  * @return bool True if the text domain was successfully localized, false otherwise.
  */
-function wp_set_script_translations( $handle, $domain = 'default', $path = null ) {
+function wp_set_script_translations( $handle, $domain = 'default', $path = '' ) {
 	global $wp_scripts;
 
 	if ( ! ( $wp_scripts instanceof WP_Scripts ) ) {

src/wp-includes/l10n.php

@@ -1065,10 +1065,7 @@ function load_script_textdomain( $handle, $domain = 'default', $path = '' ) {
 		return false;
 	}
 
-	if ( is_string( $path ) ) {
-		$path = untrailingslashit( $path );
-	}
-
+	$path   = untrailingslashit( $path );
 	$locale = determine_locale();
 
 	// If a path was given and the handle file exists simply return it.