[FIX] website: specific view ID might also change on save

Commit https://github.com/odoo/odoo/commit/29075a8e2c734624cec4f6009185616634f70dea
was written while there was an incorrect behavior related to
multi-website, oe_structure_ID and edit mode in a rare specific case
(see the second commit from this PR for detailed explanation
https://github.com/odoo/odoo/pull/30834).

That rare case was detected in 12.0 since the tour did not work on
master with the new editor (that fixed the incorrect behavior).
Basically, it was COWing the edited view even if only an oe_structure_ID
was touched.

Indeed, when saving a specific view in the HTML editor, we should also
search for its possible new ID as it could change if we also edited its
generic parent. In that case, the view will be copied and then unlinked
to preserve inherit order on the new specific tree.

addons/website/static/src/js/widgets/ace.js

@@ -40,23 +40,24 @@ var WebsiteAceEditor = AceEditor.extend({
         return this._super.apply(this, arguments).then((function () {
             var defs = [];
             if (this.currentType === 'xml') {
+                // When saving a view, the view ID might change. Thus, the
+                // active ID in the URL will be incorrect. After the save
+                // reload, that URL ID won't be found and JS will crash.
+                // We need to find the new ID (either because the view became
+                // specific or because its parent was edited too and the view
+                // got copy/unlink).
                 var selectedView = _.findWhere(this.views, {id: this._getSelectedResource()});
-                if (!selectedView.website_id[0]) {
-                    // When saving a generic view, the view will be COW'd and
-                    // replace by the specific view after the reload. Thus the id in
-                    // URL won't exist anymore. We need to find the specific ID.
-                    var context = weContext.get();
-                    defs.push(this._rpc({
-                        model: 'ir.ui.view',
-                        method: 'search_read',
-                        fields: ['id'],
-                        domain: [['key', '=', selectedView.key], ['website_id', '=', context.website_id]],
-                    }).then((function (view) {
-                        if (view[0]) {
-                            this._updateHash(view[0].id);
-                        }
-                    }).bind(this)));
-                }
+                var context = weContext.get();
+                defs.push(this._rpc({
+                    model: 'ir.ui.view',
+                    method: 'search_read',
+                    fields: ['id'],
+                    domain: [['key', '=', selectedView.key], ['website_id', '=', context.website_id]],
+                }).then((function (view) {
+                    if (view[0]) {
+                        this._updateHash(view[0].id);
+                    }
+                }).bind(this)));
             }
             return $.when.apply($, defs).then((function () {
                 window.location.reload();