Set pointer-events: none on disabled menu items to prevent ripples.

Bug: 802219
Change-Id: Id442745aebf4f71e0f4fa60510bea8b70a28d2d2
Reviewed-on: https://chromium-review.googlesource.com/c/1345713Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Sam McNally <sammc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609917}

ui/file_manager/file_manager/foreground/css/common.css

@@ -82,6 +82,7 @@ html[dir='rtl'] cr-menu.chrome-menu > .menuitem-button.right {
 
 cr-menu.chrome-menu > cr-menu-item[disabled] {
   color: rgba(51, 51, 51, 0.20);
+  pointer-events: none;
 }
 
 cr-menu.chrome-menu > cr-menu-item:not([disabled])[selected],