[gtk+] Revert "Adwaita: remove unneeded margin on dropdown menu"

[Lapo Calamandrei <lapo src gnome org>]

commit e9ee313be2bbd6cfcb37932ce9e8bf5b4743323a
Author: Lapo Calamandrei <calamandrei gmail com>
Date:   Tue May 9 13:34:49 2017 +0200

    Revert "Adwaita: remove unneeded margin on dropdown menu"
    
    This reverts commit af76e138f947d5cf3e83e4b820f7e64fd0316799.
    The margin was actually related to:
    https://bugzilla.gnome.org/show_bug.cgi?id=591258

 gtk/theme/Adwaita/_common.scss |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gtk/theme/Adwaita/_common.scss b/gtk/theme/Adwaita/_common.scss
index d2d9122..d971ac7 100644
--- a/gtk/theme/Adwaita/_common.scss
+++ b/gtk/theme/Adwaita/_common.scss
@@ -1898,6 +1898,7 @@ menubar,
 menu,
 .menu,
 .context-menu {
+  margin: 4px;
   padding: 2px 0px;
   background-color: $menu_color;
   border: 1px solid $borders_color; // adds borders in a non composited env