[IMP] extract 'set element as new widget root and replace old one in DOM' in its own method

also fix OldWidget to use it, as it had not been fixed when #replaceWith was extracted out of setElement

bzr revid: xmo@openerp.com-20120725091916-g9t5qmaeeqcceuk1

addons/web/static/src/js/corelib.js

@@ -706,13 +706,24 @@ instance.web.Widget = instance.web.Class.extend(instance.web.WidgetMixin, {
             if (this.className) { attrs['class'] = this.className; }
             $el = $(this.make(this.tagName, attrs));
         }
+        this.replaceElement($el);
+    },
+
+    /**
+     * Re-sets the widget's root element and replaces the old root element
+     * (if any) by the new one in the DOM.
+     *
+     * @param {HTMLElement | jQuery} $el
+     * @returns {*} this
+     */
+    replaceElement: function ($el) {
         var $oldel = this.$el;
         this.setElement($el);
         if ($oldel && !$oldel.is(this.$el)) {
             $oldel.replaceWith(this.$el);
         }
+        return this;
     },
-
     /**
      * Re-sets the widget's root element (el/$el/$element).
      *
@@ -723,7 +734,7 @@ instance.web.Widget = instance.web.Class.extend(instance.web.WidgetMixin, {
      *   element in the DOM
      *
      * @param {HTMLElement | jQuery} element new root element for the widget
-     * @return {*}
+     * @return {*} this
      */
     setElement: function (element) {
         if (this.$el) {

addons/web/static/src/js/coresetup.js

@@ -26,8 +26,7 @@ instance.web.OldWidget = instance.web.Widget.extend({
     renderElement: function() {
         var rendered = this.render();
         if (rendered) {
-            var $el = $(rendered);
-            this.setElement($el);
+            this.replaceElement($(rendered));
         }
         return this;
     },