Remove the language block navigation role

Closes #3319633

core/modules/language/tests/src/Functional/LanguageSwitchingTest.php

@@ -84,6 +84,7 @@ public function testLanguageBlock(): void {
     ]);
 
     $this->doTestLanguageBlockAuthenticated($block->label());
+    $this->doTestLanguageBlockRole($block->label());
     $this->doTestHomePageLinks($block->label());
     $this->doTestLanguageBlockAnonymous($block->label());
     $this->doTestLanguageBlock404($block->label(), 'system/404');
@@ -211,6 +212,26 @@ protected function doTestLanguageBlockAuthenticated($block_label): void {
     $this->assertSame(['English', 'français'], $labels, 'The language links labels are in their own language on the language switcher block.');
   }
 
+  /**
+   * Verifies that the block does not have the navigation role attribute.
+   *
+   * @param string $block_label
+   *   The label of the language switching block.
+   *
+   * @see self::testLanguageBlock()
+   */
+  protected function doTestLanguageBlockRole($block_label): void {
+    // Assert that the language switching block is displayed on the frontpage.
+    $this->drupalGet('');
+    $this->assertSession()->pageTextContains($block_label);
+
+    $block = $this->xpath('//div[@id=:id][not(@role=:role)]', [
+      ':id' => 'block-test-language-block',
+      ':role' => 'navigation',
+    ]);
+    $this->assertCount(1, $block);
+  }
+
   /**
    * For anonymous users, the "active" class is set by PHP.
    *