fixes #4395: scope dropdown menu caret in navbar to first level dropdown only

docs/assets/css/bootstrap.css

@@ -4285,7 +4285,7 @@ input[type="submit"].btn.btn-mini {
   margin-top: 3px;
 }
 
-.navbar .dropdown-menu:before {
+.navbar .nav > li > .dropdown-menu:before {
   position: absolute;
   top: -7px;
   left: 9px;
@@ -4297,7 +4297,7 @@ input[type="submit"].btn.btn-mini {
   content: '';
 }
 
-.navbar .dropdown-menu:after {
+.navbar .nav > li > .dropdown-menu:after {
   position: absolute;
   top: -6px;
   left: 10px;
@@ -4308,7 +4308,7 @@ input[type="submit"].btn.btn-mini {
   content: '';
 }
 
-.navbar-fixed-bottom .dropdown-menu:before {
+.navbar-fixed-bottom .nav > li > .dropdown-menu:before {
   top: auto;
   bottom: -7px;
   border-top: 7px solid #ccc;
@@ -4316,7 +4316,7 @@ input[type="submit"].btn.btn-mini {
   border-top-color: rgba(0, 0, 0, 0.2);
 }
 
-.navbar-fixed-bottom .dropdown-menu:after {
+.navbar-fixed-bottom .nav > li > .dropdown-menu:after {
   top: auto;
   bottom: -6px;
   border-top: 6px solid #ffffff;

less/navbar.less

@@ -266,7 +266,7 @@
 // --------------
 
 // Menu position and menu carets
-.navbar .dropdown-menu {
+.navbar .nav > li > .dropdown-menu {
   &:before {
     content: '';
     display: inline-block;
@@ -290,7 +290,7 @@
   }
 }
 // Menu position and menu caret support for dropups via extra dropup class
-.navbar-fixed-bottom .dropdown-menu {
+.navbar-fixed-bottom .nav > li > .dropdown-menu {
   &:before {
     border-top: 7px solid #ccc;
     border-top-color: @dropdownBorder;