Bug 1426128 - Fix browser_parsable_css.js failure from bug 1425868. r=ntim

MozReview-Commit-ID: 79T1qZUYv8X

--HG--
extra : rebase_source : 5121bd218a96e68b3939e62cdf1f7ac0e1d8f9d1

browser/themes/shared/customizableui/customizeMode.inc.css

@@ -462,7 +462,7 @@ toolbarpaletteitem[place=toolbar] > toolbarspring {
   /* specify width for hidpi image to fit correctly */
   width: 20px;
 %endif
-  list-style-image: url("chrome://global/skin/arrow/panelarrow-vertical.svg"));
+  list-style-image: url("chrome://global/skin/arrow/panelarrow-vertical.svg");
   -moz-context-properties: fill, stroke;
   fill: var(--arrowpanel-background);
   stroke: var(--arrowpanel-border-color);