Fix the issues reported by phpcs

Closes #3362013

src/Asset/AssetHtmlTagRenderElementTrait.php

@@ -2,6 +2,9 @@
 
 namespace Drupal\http2_server_push\Asset;
 
+/**
+ * Provides common methods for rendering HTML tag elements for assets.
+ */
 trait AssetHtmlTagRenderElementTrait {
 
   /**
@@ -11,6 +14,7 @@ trait AssetHtmlTagRenderElementTrait {
    *   A render element.
    *
    * @return bool
+   *   TRUE if the render element represents a <link rel=stylesheet>.
    */
   protected static function isLinkRelStylesheet(array $element) {
     return (isset($element['#type']) && $element['#type'] === 'html_tag')
@@ -27,6 +31,7 @@ trait AssetHtmlTagRenderElementTrait {
    *   A render element.
    *
    * @return bool
+   *   TRUE if the render element represents a <script> tag.
    */
   protected static function isScript(array $element) {
     return (isset($element['#type']) && $element['#type'] === 'html_tag')
@@ -44,6 +49,7 @@ trait AssetHtmlTagRenderElementTrait {
    *   A render element.
    *
    * @return bool
+   *   TRUE if the render element is unconditional, FALSE otherwise.
    *
    * @see \Drupal\Core\Render\Element\HtmlTag::preRenderConditionalComments
    */
@@ -60,6 +66,7 @@ trait AssetHtmlTagRenderElementTrait {
    *   The name of an attribute.
    *
    * @return bool
+   *   TRUE if the attribute value is a root-relative URL.
    */
   protected static function hasRootRelativeUrl(array $element, $attribute_name) {
     $attribute_value = $element['#attributes'][$attribute_name];