Compute index when selecting list-form row to select records

Closes #13092
(grafted from 87ea94e8f57c8329e847876083e66a0bf8a1326c)

--HG--
branch : 7.0

sao/src/view/list_form.js

@@ -165,11 +165,13 @@
                 var current_view_form;
 
                 if (event_.shiftKey) {
+                    let i = 0;
                     for (const other_view_form of this._view_forms) {
-                        if (other_view_forms.record === this.record) {
+                        if (other_view_form.record === this.record) {
                             current_view_form = other_view_form;
                             break;
                         }
+                        i++;
                     }
                     this.select_records(i, next_form_idx);
                 } else {