Merge branch '5.3' into 5.4

* 5.3:
  The method renderForm generate a 422 Unprocessable Entity if the form is invalid. So we can’t pass in the success method. I suggest to replace it with the complete method.
  Updating sass-loader version
  Removing MooTools (!)

Author: javiereguiluz

components/css_selector.rst

@@ -40,7 +40,7 @@ long and unwieldy expressions.
 Many developers -- particularly web developers -- are more comfortable
 using CSS selectors to find elements. As well as working in stylesheets,
 CSS selectors are used in JavaScript with the ``querySelectorAll()`` function
-and in popular JavaScript libraries such as jQuery, Prototype and MooTools.
+and in popular JavaScript libraries such as jQuery.
 
 CSS selectors are less powerful than XPath, but far easier to write, read
 and understand. Since they are less powerful, almost all CSS selectors can

form/dynamic_form_modification.rst

@@ -568,11 +568,11 @@ field according to the current selection in the ``sport`` field:
         url : $form.attr('action'),
         type: $form.attr('method'),
         data : data,
-        success: function(html) {
+        complete: function(html) {
           // Replace current position field ...
           $('#meetup_position').replaceWith(
             // ... with the returned one from the AJAX response.
-            $(html).find('#meetup_position')
+            $(html.responseText).find('#meetup_position')
           );
           // Position field now displays the appropriate positions.
         }

frontend/encore/simple-example.rst

@@ -299,19 +299,19 @@ Encore. When you do, you'll see an error!
 .. code-block:: terminal
 
     >   Error: Install sass-loader & sass to use enableSassLoader()
-    >     yarn add sass-loader@^10.0.0 sass --dev
+    >     yarn add sass-loader@^12.0.0 sass --dev
 
 Encore supports many features. But, instead of forcing all of them on you, when
 you need a feature, Encore will tell you what you need to install. Run:
 
 .. code-block:: terminal
 
     # if you use the Yarn package manager
-    $ yarn add sass-loader@^10.0.0 sass --dev
+    $ yarn add sass-loader@^12.0.0 sass --dev
     $ yarn encore dev --watch
 
     # if you use the npm package manager
-    $ npm install sass-loader@^10.0.0 sass --save-dev
+    $ npm install sass-loader@^12.0.0 sass --save-dev
     $ npm run watch
 
 Your app now supports Sass. Encore also supports LESS and Stylus. See