Ticket #57414: 57414.2.patch

src/wp-content/themes/twentyten/editor-blocks.css

@@ -368 +368 @@
 :root .editor-styles-wrapper .has-white-background-color:visited {
         background-color: #fff;
 }
+
+/* Inserter Icon */
+
+.editor-styles-wrapper .block-editor-inserter path {
+        color: #fff;
+}