Allow D8 link handler to work with named field properties

gh-192

src/Drupal/Driver/Fields/Drupal8/LinkHandler.php

@@ -11,21 +11,22 @@ class LinkHandler extends AbstractHandler {
    * {@inheritdoc}
    */
   public function expand($values) {
-    $return = [];
+    $return_values = [];
     foreach ($values as $value) {
       // 'options' is required to be an array, otherwise the utility class
       // Drupal\Core\Utility\UnroutedUrlAssembler::assemble() will complain.
-      $options = [];
-      if (!empty($value[2])) {
-        parse_str($value[2], $options);
-      }
-      $return[] = [
-        'options' => $options,
-        'title' => $value[0],
-        'uri' => $value[1],
+      $return_value = [
+        'title' => $value['title'] ?? $value[0] ?? NULL,
+        'uri' => $value['uri'] ?? $value[1] ?? NULL,
+        'options' => [],
       ];
+      $options = $value['options'] ?? $value[2] ?? NULL;
+      if ($options) {
+        parse_str($options, $return_value['options']);
+      }
+      $return_values[] = $return_value;
     }
-    return $return;
+    return $return_values;
   }
 
 }