Backport type fixes

Author: nicolas-grekas

Countries.php

@@ -109,7 +109,7 @@ public static function getAlpha3Name(string $alpha3Code, string $displayLocale =
      *
      * @return string[]
      */
-    public static function getNames($displayLocale = null): array
+    public static function getNames(?string $displayLocale = null): array
     {
         return self::asort(self::readEntry(['Names'], $displayLocale), $displayLocale);
     }
@@ -121,7 +121,7 @@ public static function getNames($displayLocale = null): array
      *
      * @return string[]
      */
-    public static function getAlpha3Names($displayLocale = null): array
+    public static function getAlpha3Names(?string $displayLocale = null): array
     {
         $alpha2Names = self::getNames($displayLocale);
         $alpha3Names = [];

Languages.php

@@ -159,7 +159,7 @@ public static function getAlpha3Name(string $language, string $displayLocale = n
      *
      * @return string[]
      */
-    public static function getAlpha3Names($displayLocale = null): array
+    public static function getAlpha3Names(string $displayLocale = null): array
     {
         $alpha2Names = self::getNames($displayLocale);
         $alpha3Names = [];

Locales.php

@@ -67,7 +67,7 @@ public static function getName(string $locale, string $displayLocale = null): st
     /**
      * @return string[]
      */
-    public static function getNames($displayLocale = null): array
+    public static function getNames(string $displayLocale = null): array
     {
         return self::asort(self::readEntry(['Names'], $displayLocale), $displayLocale);
     }

Scripts.php

@@ -51,7 +51,7 @@ public static function getName(string $script, string $displayLocale = null): st
     /**
      * @return string[]
      */
-    public static function getNames($displayLocale = null): array
+    public static function getNames(string $displayLocale = null): array
     {
         return self::asort(self::readEntry(['Names'], $displayLocale), $displayLocale);
     }

Util/IntlTestHelper.php

@@ -30,7 +30,7 @@ class IntlTestHelper
     /**
      * Should be called before tests that work fine with the stub implementation.
      */
-    public static function requireIntl(TestCase $testCase, $minimumIcuVersion = null)
+    public static function requireIntl(TestCase $testCase, string $minimumIcuVersion = null)
     {
         if (null === $minimumIcuVersion) {
             $minimumIcuVersion = Intl::getIcuStubVersion();
@@ -64,7 +64,7 @@ public static function requireIntl(TestCase $testCase, $minimumIcuVersion = null
      * Should be called before tests that require a feature-complete intl
      * implementation.
      */
-    public static function requireFullIntl(TestCase $testCase, $minimumIcuVersion = null)
+    public static function requireFullIntl(TestCase $testCase, string $minimumIcuVersion = null)
     {
         // We only run tests if the intl extension is loaded...
         if (!Intl::isExtensionLoaded()) {