dropdowns.scss: Fix style issues after review

Signed-off-by: David Wagner <david@marvid.fr>

app/assets/stylesheets/framework/dropdowns.scss

@@ -28,7 +28,6 @@
   .dropdown-toggle,
   .dropdown-menu-toggle {
     @include chevron-active;
-
     border-color: $dropdown-toggle-hover-border-color;
   }
 }
@@ -81,22 +80,18 @@
 
   &:hover {
     @include chevron-active;
-
     border-color: $dropdown-toggle-hover-border-color;
   }
 
   &:focus:active {
     @include chevron-active;
-
     border-color: $dropdown-toggle-active-border-color;
   }
 }
 
 .dropdown-menu-toggle {
   @extend .dropdown-toggle;
-
   padding-right: 20px;
-
   position: relative;
   width: 160px;
   text-overflow: ellipsis;