MC-17449: Deliver CSS critical path to 2.2.x

- Remove void return type;
- Fix cyclomatic complexity;

Author: adifucan

app/code/Magento/Theme/Controller/Result/AsyncCssPlugin.php

@@ -37,7 +37,7 @@ public function __construct(ScopeConfigInterface $scopeConfig)
      * @param Http $subject
      * @return void
      */
-    public function beforeSendResponse(Http $subject): void
+    public function beforeSendResponse(Http $subject)
     {
         $content = $subject->getContent();
 

lib/internal/Magento/Framework/View/Page/Config/Reader/Head.php

@@ -7,6 +7,7 @@
 
 use Magento\Framework\View\Layout;
 use Magento\Framework\View\Page\Config as PageConfig;
+use Magento\Framework\View\Page\Config\Structure;
 
 /**
  * Head structure reader is intended for collecting assets, title and metadata
@@ -85,43 +86,55 @@ function (Layout\Element $current, Layout\Element $next) {
         );
 
         foreach ($nodes as $node) {
-            switch ($node->getName()) {
-                case self::HEAD_CSS:
-                case self::HEAD_SCRIPT:
-                case self::HEAD_LINK:
-                case self::HEAD_FONT:
-                    $this->addContentTypeByNodeName($node);
-                    $pageConfigStructure->addAssets($node->getAttribute('src'), $this->getAttributes($node));
-                    break;
-
-                case self::HEAD_REMOVE:
-                    $pageConfigStructure->removeAssets($node->getAttribute('src'));
-                    break;
-
-                case self::HEAD_TITLE:
-                    $pageConfigStructure->setTitle(new \Magento\Framework\Phrase($node));
-                    break;
-
-                case self::HEAD_META:
-                    $this->setMetadata($pageConfigStructure, $node);
-                    break;
-
-                case self::HEAD_ATTRIBUTE:
-                    $pageConfigStructure->setElementAttribute(
-                        PageConfig::ELEMENT_TYPE_HEAD,
-                        $node->getAttribute('name'),
-                        $node->getAttribute('value')
-                    );
-                    break;
-
-                default:
-                    break;
-            }
+            $this->processNode($node, $pageConfigStructure);
         }
 
         return $this;
     }
 
+    /**
+     * Process given node based on it's name.
+     *
+     * @param Layout\Element $node
+     * @param Structure $pageConfigStructure
+     * @return void
+     */
+    private function processNode(Layout\Element $node, Structure $pageConfigStructure)
+    {
+        switch ($node->getName()) {
+            case self::HEAD_CSS:
+            case self::HEAD_SCRIPT:
+            case self::HEAD_LINK:
+            case self::HEAD_FONT:
+                $this->addContentTypeByNodeName($node);
+                $pageConfigStructure->addAssets($node->getAttribute('src'), $this->getAttributes($node));
+                break;
+
+            case self::HEAD_REMOVE:
+                $pageConfigStructure->removeAssets($node->getAttribute('src'));
+                break;
+
+            case self::HEAD_TITLE:
+                $pageConfigStructure->setTitle(new \Magento\Framework\Phrase($node));
+                break;
+
+            case self::HEAD_META:
+                $this->setMetadata($pageConfigStructure, $node);
+                break;
+
+            case self::HEAD_ATTRIBUTE:
+                $pageConfigStructure->setElementAttribute(
+                    PageConfig::ELEMENT_TYPE_HEAD,
+                    $node->getAttribute('name'),
+                    $node->getAttribute('value')
+                );
+                break;
+
+            default:
+                break;
+        }
+    }
+
     /**
      * Get all attributes for current dom element
      *