Update Yaru to new Dash-to-Dock code (#4051)

Some changes were required in the scss to make Dash to Dock
compatible with Gnome Shell 46, while also keeping compatibility
with Gnome Shell 45. These are those changes.

gnome-shell/src/gnome-shell-sass/_dock.scss

@@ -15,6 +15,8 @@ $dock_edge_items_padding: $dash_padding - $dock_spacing;
 $dock_fixed_inner_margin: $dock_side_margin;
 $dock_icons_distance: 4px;
 
+$remark_color: rgba(238, 238, 236, 0.2);
+
 @function shrink($val) {
     @return round($val / 4);
 }
@@ -186,7 +188,8 @@ $dock_style_modes: [null, shrink, extended, extended-shrink];
                     0, $dock_icons_distance / 2);
 
                 .app-well-app,
-                .show-apps {
+                .show-apps,
+                .overview-tile {
                     @include set-internal-children-property($side, padding, $spacing);
                     padding-#{$side}: $padding + $side_margin;
                     padding-#{opposite($side)}: $padding;
@@ -197,7 +200,7 @@ $dock_style_modes: [null, shrink, extended, extended-shrink];
                         background-image: none;
                     }
                     &.focused .overview-icon {
-                        background-color: rgba(238, 238, 236, 0.2);
+                        background-color: $remark_color;
                     }
 
                     .app-well-app-running-dot {
@@ -230,6 +233,20 @@ $dock_style_modes: [null, shrink, extended, extended-shrink];
     }
 }
 
+.overview-tile {
+    margin: 0px;
+    padding: 0px;
+    border: 0px;
+}
+
+.overview-tile .overview-icon, .show-apps .overview-icon {
+    background-color: rgba(255,255,255,0);
+}
+
+.overview-tile:hover .overview-icon, .overview-tile.focused .overview-icon, .show-apps:hover .overview-icon {
+    background-color: $remark_color;
+}
+
 @each $side in $dock_sides {
     @each $style_mode in $dock_style_modes {
         $is_shrink: str-index(#{$style_mode}, shrink) !=null;