diff --git a/addons/mass_mailing/static/src/js/mass_mailing_widget.js b/addons/mass_mailing/static/src/js/mass_mailing_widget.js
index 818d08d2970..789f15a8fda 100644
--- a/addons/mass_mailing/static/src/js/mass_mailing_widget.js
+++ b/addons/mass_mailing/static/src/js/mass_mailing_widget.js
@@ -115,10 +115,6 @@ var MassMailingFieldHtml = FieldHtml.extend({
         this.$content.find('.o_layout').addBack().data('name', 'Mailing');
         // We don't want to drop snippets directly within the wysiwyg.
         this.$content.removeClass('o_editable');
-        // Force compute CSS rules even without the style-inline node option.
-        if (this.mode === 'edit' && !this.cssRules) {
-            this.cssRules = convertInline.getCSSRules(this.wysiwyg.getEditable()[0].ownerDocument);
-        }
     },
     /**
      * Returns true if the editable area is empty.
diff --git a/addons/web_editor/static/src/js/backend/convert_inline.js b/addons/web_editor/static/src/js/backend/convert_inline.js
index 8416e43316b..707a673b97a 100644
--- a/addons/web_editor/static/src/js/backend/convert_inline.js
+++ b/addons/web_editor/static/src/js/backend/convert_inline.js
@@ -955,14 +955,6 @@ FieldHtml.include({
     // Public
     //--------------------------------------------------------------------------
 
-    _createWysiwygIntance: function () {
-        return this._super(...arguments).then(() => {
-            if (this.nodeOptions['style-inline'] && this.mode === "edit") {
-                this.cssRules = getCSSRules(this.wysiwyg.getEditable()[0].ownerDocument);
-            }
-        });
-    },
-
     /**
      * @override
      */