fixes #9439: use overflow: auto on navbar collapse

dist/css/bootstrap.css

@@ -3154,10 +3154,10 @@ button.close {
 }
 
 .navbar-collapse {
-  max-height: 360px;
+  max-height: 340px;
   padding: 5px 15px;
   overflow-x: visible;
-  overflow-y: scroll;
+  overflow-y: auto;
   border-top: 1px solid #e6e6e6;
   box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.1);
   -webkit-overflow-scrolling: touch;

less/navbar.less

@@ -59,9 +59,9 @@
 
   // This is not automatically added to the `.navbar-fixed-top` because it causes
   // z-index bugs in iOS7 (possibly earlier).
-  max-height: 360px;
+  max-height: 340px;
   overflow-x: visible;
-  overflow-y: scroll;
+  overflow-y: auto;
   -webkit-overflow-scrolling: touch;
 
   @media (min-width: @grid-float-breakpoint) {