Revert "Issue #3172166 by Pooja Ganjage, ekes, Megha_kundar, tstoeckler,...

Revert "Issue #3172166 by Pooja Ganjage, ekes, Megha_kundar, tstoeckler, mbovan, Spokje, alexpott: Element::properties() produces notices if given an array with integer keys"

This reverts commit 089376cf.

core/lib/Drupal/Core/Render/Element.php

@@ -24,7 +24,7 @@ class Element {
    *   TRUE of the key is a property, FALSE otherwise.
    */
   public static function property($key) {
-    return is_string($key) && $key[0] == '#';
+    return $key[0] == '#';
   }
 
   /**

core/tests/Drupal/Tests/Core/Render/ElementTest.php

@@ -19,7 +19,6 @@ public function testProperty() {
     $this->assertTrue(Element::property('#property'));
     $this->assertFalse(Element::property('property'));
     $this->assertFalse(Element::property('property#'));
-    $this->assertFalse(Element::property(0));
   }
 
   /**
@@ -30,16 +29,13 @@ public function testProperties() {
       '#property1' => 'property1',
       '#property2' => 'property2',
       'property3' => 'property3',
-      0 => [],
     ];
 
     $properties = Element::properties($element);
 
-    $this->assertCount(2, $properties);
     $this->assertContains('#property1', $properties);
     $this->assertContains('#property2', $properties);
     $this->assertNotContains('property3', $properties);
-    $this->assertNotContains(0, $properties);
   }
 
   /**