[FIX] web_editor: review drag and drop in the editor

Forward-port of https://github.com/odoo/odoo/commit/be689c53c13330832510c8cef332ac862d4ed5e8
was missed from 11.0.

closes odoo/odoo#31971

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/web_editor/static/src/js/editor/snippets.editor.js

@@ -370,6 +370,7 @@ var SnippetEditor = Widget.extend({
      */
     _onDragAndDropStart: function () {
         var self = this;
+        this.dropped = false;
         self.size = {
             width: self.$target.width(),
             height: self.$target.height()
@@ -415,10 +416,21 @@ var SnippetEditor = Widget.extend({
      * 'move' button.
      *
      * @private
+     * @param {Event} ev
+     * @param {Object} ui
      */
-    _onDragAndDropStop: function () {
+    _onDragAndDropStop: function (ev, ui) {
         var self = this;
 
+        // TODO lot of this is duplicated code of the d&d feature of snippets
+        if (!this.dropped) {
+            var $el = $.nearest({x: ui.position.left, y: ui.position.top}, '.oe_drop_zone').first();
+            if ($el.length) {
+                $el.after(this.$target);
+                this.dropped = true;
+            }
+        }
+
         $('.oe_drop_zone').droppable('destroy').remove();
 
         var prev = this.$target.first()[0].previousSibling;