[FIX] web_editor: replacing selected text in a hierarchy on Firefox

When following these steps on Firefox:
- Select all text in a bold link (triple click)
- Type some text

The typed text did not replace the selected text but was instead put
at the front of it.

addons/web_editor/static/src/js/summernote.js

@@ -550,6 +550,13 @@ dom.removeBetween = function (sc, so, ec, eo, towrite) {
         so = 0;
         eo = 1;
     }
+
+    var parentNode = sc && sc.parentNode;
+    if (parentNode && sc.tagName === 'BR') {
+        sc = parentNode;
+        ec = parentNode;
+    }
+
     return {
         sc: sc,
         so: so,
@@ -1164,9 +1171,9 @@ $.summernote.pluginEvents.visible = function (event, editor, layoutInfo) {
     if (!r) return;
 
     if (!r.isCollapsed()) {
-        if (dom.isCell(dom.node(r.sc)) || dom.isCell(dom.node(r.ec))) {
+        if ((dom.isCell(dom.node(r.sc)) || dom.isCell(dom.node(r.ec))) && dom.node(r.sc) !== dom.node(r.ec)) {
             remove_table_content(r);
-            r = range.create(r.ec, 0).select();
+            r = range.create(r.ec, 0);
         } else {
             r = r.deleteContents(true);
         }