[CLEANUP] Drop some comments from testcases (#973)

These comments are no longer needed now that the
abstract base classes have their own testcases.

Author: oliverklee

Diff for: tests/Unit/CSSList/AtRuleBlockListTest.php

@@ -18,10 +18,6 @@
  */
 final class AtRuleBlockListTest extends TestCase
 {
-    /*
-     * Tests for the implemented interfaces and superclasses
-     */
-
     /**
      * @test
      */
@@ -72,10 +68,6 @@ public function isCSSList(): void
         self::assertInstanceOf(CSSList::class, $subject);
     }
 
-    /*
-     * not grouped yet
-     */
-
     /**
      * @test
      */

Diff for: tests/Unit/CSSList/DocumentTest.php

@@ -24,10 +24,6 @@
  */
 final class DocumentTest extends TestCase
 {
-    /*
-     * Tests for the implemented interfaces and superclasses
-     */
-
     /**
      * @test
      */
@@ -64,10 +60,6 @@ public function isCSSList(): void
         self::assertInstanceOf(CSSList::class, $subject);
     }
 
-    /*
-     * not grouped yet
-     */
-
     /**
      * @test
      */

Diff for: tests/Unit/CSSList/KeyFrameTest.php

@@ -17,10 +17,6 @@
  */
 final class KeyFrameTest extends TestCase
 {
-    /*
-     * Tests for the implemented interfaces and superclasses
-     */
-
     /**
      * @test
      */
@@ -61,10 +57,6 @@ public function isCSSList(): void
         self::assertInstanceOf(CSSList::class, $subject);
     }
 
-    /*
-     * not grouped yet
-     */
-
     /**
      * @test
      */