Remove vendor prefixes for linear-gradient CSS

CHANGELOG

@@ -2,6 +2,7 @@ Please view this file on the master branch, on stable branches it's out of date.
 
 v 8.12.0 (unreleased)
   - Add two-factor recovery endpoint to internal API !5510
+  - Remove vendor prefixes for linear-gradient CSS (ClemMakesApps)
   - Add font color contrast to external label in admin area (ClemMakesApps)
   - Change merge_error column from string to text type
   - Reduce contributions calendar data payload (ClemMakesApps)

app/assets/stylesheets/framework/nav.scss

@@ -8,10 +8,7 @@
   height: 30px;
   transition-duration: .3s;
   -webkit-transform: translateZ(0);
-  background: -webkit-linear-gradient($gradient-direction, rgba($gradient-color, 0.4), $gradient-color 45%);
-  background: -o-linear-gradient($gradient-direction, rgba($gradient-color, 0.4), $gradient-color 45%);
-  background: -moz-linear-gradient($gradient-direction, rgba($gradient-color, 0.4), $gradient-color 45%);
-  background: linear-gradient($gradient-direction, rgba($gradient-color, 0.4), $gradient-color 45%);
+  background: linear-gradient(to $gradient-direction, $gradient-color 45%, rgba($gradient-color, 0.4));
 
   &.scrolling {
     visibility: visible;