[REF] website: make mutation processing more robust

This probably does not change much but it short-circuit a bunch of code
when we click outside of an editable zone and something in the DOM
happens. Allows for easier debugging of mutations. It also avoids the
creation of a jQuery object when the mutation is about changing a
contenteditable attribute, I guess any small perf improvement should be
welcomed.

Related to runbot-18747

X-original-commit: f93a2da57e1424898fbf6e157945e2afa97be89e
Part-of: odoo/odoo#148728

addons/website/static/src/components/wysiwyg_adapter/wysiwyg_adapter.js

@@ -398,11 +398,17 @@ export class WysiwygAdapterComponent extends Wysiwyg {
             // generated a new stack and break the "redo" of the editor.
             this.odooEditor.automaticStepSkipStack();
             for (const record of records) {
-                const $savable = $(record.target).closest(this.savableSelector);
-
                 if (record.attributeName === 'contenteditable') {
                     continue;
                 }
+
+                const $savable = $(record.target).closest(this.savableSelector);
+                if (!$savable.length) {
+                    continue;
+                }
+
+                // Mark any savable element dirty if any tracked mutation occurs
+                // inside of it.
                 $savable.not('.o_dirty').each(function () {
                     if (!this.hasAttribute('data-oe-readonly')) {
                         this.classList.add('o_dirty');