[polari] ui: Don't set .titlebar class on headerbars

[Florian Müllner <fmuellner src gnome org>]

commit a00b43daa4fc5ab58eb7145f2ef12823f92501a7
Author: Florian Müllner <fmuellner gnome org>
Date:   Wed Dec 23 22:51:29 2015 +0100

    ui: Don't set .titlebar class on headerbars
    
    The parent box is the actual titlebar, so don't pretend otherwise.

 data/resources/main-window.ui |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)
---
diff --git a/data/resources/main-window.ui b/data/resources/main-window.ui
index f1472d3..9bad098 100644
--- a/data/resources/main-window.ui
+++ b/data/resources/main-window.ui
@@ -30,7 +30,6 @@
             <property name="show_close_button">True</property>
             <style>
               <class name="polari-titlebar-left"/>
-              <class name="titlebar"/>
             </style>
             <child>
               <object class="GtkMenuButton" id="join_menu_button">
@@ -84,7 +83,6 @@
             <property name="show_close_button">True</property>
             <style>
               <class name="polari-titlebar-right"/>
-              <class name="titlebar"/>
             </style>
             <!-- Use a custom title widget to enable markup for subtitles
                  (for URLs in channel topics); other than that, we want