[gtk+] HighContrast: more combobox fixes

[Cosimo Cecchi <cosimoc src gnome org>]

commit 0f3f2e7f9c7563826cde54c29b55743809e1f1ea
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Tue Jan 5 10:01:33 2016 -0800

    HighContrast: more combobox fixes
    
    Taken from Adwaita.

 gtk/theme/HighContrast/_common.scss |   14 ++++++++------
 gtk/theme/HighContrast/gtk.css      |   13 +++++++------
 2 files changed, 15 insertions(+), 12 deletions(-)
---
diff --git a/gtk/theme/HighContrast/_common.scss b/gtk/theme/HighContrast/_common.scss
index d367dd8..9da926f 100644
--- a/gtk/theme/HighContrast/_common.scss
+++ b/gtk/theme/HighContrast/_common.scss
@@ -767,13 +767,15 @@ combobox {
       border-radius: 0 3px 3px 0;
     }
   }
-  & > button.combo, & > button.combo:backdrop {
-    // It is needed to specify the backdrop button or it gets overridden
-    border-radius: 0 3px 3px 0;
-    border-left-style: none;
+  & > button.combo:not(:only-child) {
+    &:dir(ltr) {
+      border-top-left-radius: 0;
+      border-bottom-left-radius: 0;
+      border-left-style: none;
+    }
     &:dir(rtl) {
-      border-radius: 3px 0 0 3px;
-      border-left-style: solid;
+      border-top-right-radius: 0;
+      border-bottom-right-radius: 0;
       border-right-style: none;
     }
   }
diff --git a/gtk/theme/HighContrast/gtk.css b/gtk/theme/HighContrast/gtk.css
index 0a2b696..99d3541 100644
--- a/gtk/theme/HighContrast/gtk.css
+++ b/gtk/theme/HighContrast/gtk.css
@@ -912,13 +912,14 @@ combobox {
     border-radius: 3px 0 0 3px; }
     combobox > entry.combo:dir(rtl) {
       border-radius: 0 3px 3px 0; }
-  combobox > button.combo, combobox > button.combo:backdrop {
-    border-radius: 0 3px 3px 0;
+  combobox > button.combo:not(:only-child):dir(ltr) {
+    border-top-left-radius: 0;
+    border-bottom-left-radius: 0;
     border-left-style: none; }
-    combobox > button.combo:dir(rtl), combobox > button.combo:backdrop:dir(rtl) {
-      border-radius: 3px 0 0 3px;
-      border-left-style: solid;
-      border-right-style: none; }
+  combobox > button.combo:not(:only-child):dir(rtl) {
+    border-top-right-radius: 0;
+    border-bottom-right-radius: 0;
+    border-right-style: none; }
 
 /************
  * Toolbars *