Added sidebar button to default URL bar

src/browser/themes/shared/zen-browser-shared.css

@@ -11,7 +11,8 @@
 
 #urlbar {
   border: 1px solid light-dark(#ddd, #4a4a4a);
-  border-radius: 5px;
+  border-radius: 999px;
+  overflow: hidden;
   padding: 1px 1px;
 }
 
@@ -21,6 +22,10 @@
   width: 100%;
 }
 
+#urlbar[focused="true"] {
+  overflow: visible;
+}
+
 #urlbar[focused="true"] > #urlbar-background,
 #searchbar:focus-within {
   box-shadow: none !important;