Issue #2187335 by mondrake: Cannot delete image styles from UI any longer.

core/modules/image/lib/Drupal/image/Entity/ImageStyle.php

@@ -41,7 +41,8 @@
  *   },
  *   links = {
  *     "flush-form" = "image.style_flush",
- *     "edit-form" = "image.style_edit"
+ *     "edit-form" = "image.style_edit",
+ *     "delete-form" = "image.style_delete"
  *   }
  * )
  */

core/modules/image/lib/Drupal/image/Form/ImageEffectFormBase.php

@@ -86,6 +86,7 @@ public function buildForm(array $form, array &$form_state, ImageStyleInterface $
       '#value' => $request->query->has('weight') ? (int) $request->query->get('weight') : $this->imageEffect->getWeight(),
     );
 
+    $image_style_uri = $this->imageStyle->urlInfo('edit-form');
     $form['actions'] = array('#type' => 'actions');
     $form['actions']['submit'] = array(
       '#type' => 'submit',
@@ -94,7 +95,8 @@ public function buildForm(array $form, array &$form_state, ImageStyleInterface $
     $form['actions']['cancel'] = array(
       '#type' => 'link',
       '#title' => $this->t('Cancel'),
-      '#href' => 'admin/config/media/image-styles/manage/' . $this->imageStyle->id(),
+      '#route_name' => $image_style_uri['route_name'],
+      '#route_parameters' => $image_style_uri['route_parameters'],
     );
     return $form;
   }

core/modules/image/lib/Drupal/image/Tests/ImageAdminStylesTest.php

@@ -67,10 +67,12 @@ function testNumericStyleName() {
    * General test to add a style, add/remove/edit effects to it, then delete it.
    */
   function testStyle() {
+    $admin_path = 'admin/config/media/image-styles';
+
     // Setup a style to be created and effects to add to it.
     $style_name = strtolower($this->randomName(10));
     $style_label = $this->randomString();
-    $style_path = 'admin/config/media/image-styles/manage/' . $style_name;
+    $style_path = $admin_path . '/manage/' . $style_name;
     $effect_edits = array(
       'image_resize' => array(
         'data[width]' => 100,
@@ -106,9 +108,15 @@ function testStyle() {
       'name' => $style_name,
       'label' => $style_label,
     );
-    $this->drupalPostForm('admin/config/media/image-styles/add', $edit, t('Create new style'));
+    $this->drupalPostForm($admin_path . '/add', $edit, t('Create new style'));
     $this->assertRaw(t('Style %name was created.', array('%name' => $style_label)));
 
+    // Ensure that the expected entity operations are there.
+    $this->drupalGet($admin_path);
+    $this->assertLinkByHref($style_path);
+    $this->assertLinkByHref($style_path . '/flush');
+    $this->assertLinkByHref($style_path . '/delete');
+
     // Add effect form.
 
     // Add each sample effect to the style.