Tests: Fix tests failing due to assertContains() using strict checking.

Since PHPUnit 8.0.2, the `assertContains()` method, when checking whether a value exists in an array, will do a strict type comparison of the values.

This caused a couple of tests to fail. Using the correct data type in the test fixes that.

References:
* https://github.com/sebastianbergmann/phpunit/blob/8.0.6/ChangeLog-8.0.md#802---2019-02-07
* sebastianbergmann/phpunit#3511
* sebastianbergmann/phpunit@6205f33

Follow-up to [51559-51570].

Props jrf.
See #46149.

git-svn-id: https://develop.svn.wordpress.org/trunk@51571 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

tests/phpunit/tests/comment/getPageOfComment.php

@@ -485,7 +485,7 @@ public function test_page_number_when_unapproved_comments_are_included_for_curre
 
 		remove_filter( 'wp_get_current_commenter', array( $this, 'get_current_commenter' ) );
 
-		$this->assertContains( $new_unapproved, wp_list_pluck( $comments, 'comment_ID' ) );
+		$this->assertContains( (string) $new_unapproved, wp_list_pluck( $comments, 'comment_ID' ) );
 	}
 
 	public function get_current_commenter() {
@@ -542,7 +542,7 @@ public function test_page_number_when_unapproved_comments_are_included_for_curre
 			)
 		);
 
-		$this->assertContains( $new_unapproved, wp_list_pluck( $comments, 'comment_ID' ) );
+		$this->assertContains( (string) $new_unapproved, wp_list_pluck( $comments, 'comment_ID' ) );
 
 		wp_set_current_user( $current_user );
 	}

tests/phpunit/tests/rest-api/rest-post-meta-fields.php

@@ -891,8 +891,8 @@ public function test_set_value_multiple_custom_schema() {
 		$meta = get_post_meta( self::$post_id, 'test_custom_schema_multi', false );
 		$this->assertNotEmpty( $meta );
 		$this->assertCount( 2, $meta );
-		$this->assertContains( 2, $meta );
-		$this->assertContains( 8, $meta );
+		$this->assertContains( '2', $meta );
+		$this->assertContains( '8', $meta );
 	}
 
 	/**

tests/phpunit/tests/rest-api/rest-term-meta-fields.php

@@ -838,8 +838,8 @@ public function test_set_value_multiple_custom_schema() {
 		$meta = get_term_meta( self::$category_id, 'test_custom_schema_multi', false );
 		$this->assertNotEmpty( $meta );
 		$this->assertCount( 2, $meta );
-		$this->assertContains( 2, $meta );
-		$this->assertContains( 8, $meta );
+		$this->assertContains( '2', $meta );
+		$this->assertContains( '8', $meta );
 	}
 
 	/**