fixes #5478: remove double background color on dropdown links

docs/assets/css/bootstrap.css

@@ -990,7 +990,7 @@ input[type="color"],
   display: inline-block;
   height: 20px;
   padding: 4px 6px;
-  margin-bottom: 9px;
+  margin-bottom: 10px;
   font-size: 14px;
   line-height: 20px;
   color: #555555;
@@ -2823,7 +2823,6 @@ table th[class*="span"],
 .dropdown-submenu:hover > a {
   color: #ffffff;
   text-decoration: none;
-  background-color: #0088cc;
   background-color: #0081c2;
   background-image: -moz-linear-gradient(top, #0088cc, #0077b3);
   background-image: -webkit-gradient(linear, 0 0, 0 100%, from(#0088cc), to(#0077b3));
@@ -2838,7 +2837,6 @@ table th[class*="span"],
 .dropdown-menu .active > a:hover {
   color: #ffffff;
   text-decoration: none;
-  background-color: #0088cc;
   background-color: #0081c2;
   background-image: -moz-linear-gradient(top, #0088cc, #0077b3);
   background-image: -webkit-gradient(linear, 0 0, 0 100%, from(#0088cc), to(#0077b3));

less/dropdowns.less

@@ -90,7 +90,6 @@
 .dropdown-submenu:hover > a {
   text-decoration: none;
   color: @dropdownLinkColorHover;
-  background-color: @dropdownLinkBackgroundHover;
   #gradient > .vertical(@dropdownLinkBackgroundHover, darken(@dropdownLinkBackgroundHover, 5%));
 }
 
@@ -101,7 +100,6 @@
   color: @dropdownLinkColorHover;
   text-decoration: none;
   outline: 0;
-  background-color: @dropdownLinkBackgroundActive;
   #gradient > .vertical(@dropdownLinkBackgroundActive, darken(@dropdownLinkBackgroundActive, 5%));
 }