Adwaita: make selection visible in treeview derived widgets

See https://bugzilla.gnome.org/show_bug.cgi?id=757503

gtk/theme/Adwaita/_common.scss

@@ -88,7 +88,6 @@ $asset_suffix: if($variant=='dark', '-dark', '');
   }
 }
 
-textview text,
 .view {
   color: $text_color;
   background-color: $base_color;
@@ -98,19 +97,6 @@ textview text,
     background-color: $backdrop_base_color;
   }
 
-  selection,
-  selection:focus { @extend %selected_items; }
-}
-
-iconview {
-  color: $text_color;
-  background-color: $base_color;
-
-  &:backdrop {
-    color: $backdrop_text_color;
-    background-color: $backdrop_base_color;
-  }
-
   &:selected,
   &:selected:focus {
     @extend %selected_items;
@@ -118,6 +104,15 @@ iconview {
   }
 }
 
+textview text {
+  @extend .view;
+
+  selection,
+  selection:focus { @extend %selected_items; }
+}
+
+iconview { @extend .view; }
+
 .rubberband,
 rubberband {
   border: 1px solid darken($selected_bg_color, 10%);
@@ -1430,7 +1425,8 @@ treeview.view {
 
   & rubberband { @extend rubberband; } // to avoid borders being overridden by the previously set props
 
-  &:selected {
+  &:selected,
+  &:selected:focus {
     border-radius: 0;
     @extend %selected_items;
   }