Changed last-child to first-child

As noted by @jerem the first child will actually be the last shown

less/navbar.less

@@ -271,7 +271,7 @@
       }
     }
 
-    &.navbar-right:last-child {
+    &.navbar-right:first-child {
       margin-right: -@navbar-padding-horizontal;
     }
   }
@@ -326,8 +326,8 @@
     padding-bottom: 0;
     .box-shadow(none);
 
-    // Outdent the form if last child to line up with content down the page
-    &.navbar-right:last-child {
+    // Outdent the form if first child to line up with content down the page
+    &.navbar-right:first-child {
       margin-right: -@navbar-padding-horizontal;
     }
   }
@@ -375,8 +375,8 @@
     margin-left: @navbar-padding-horizontal;
     margin-right: @navbar-padding-horizontal;
 
-    // Outdent the form if last child to line up with content down the page
-    &.navbar-right:last-child {
+    // Outdent the form if first child to line up with content down the page
+    &.navbar-right:first-child {
       margin-right: 0;
     }
   }