Bookmarks: when focused, increase z-index so outline is not cutoff when other items are highlighted

Bug: 854081
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: Ib73d38ea25ca0ea70e3322b1e5066cd6a2b5ded9
Reviewed-on: https://chromium-review.googlesource.com/1106421Reviewed-by: calamity <calamity@chromium.org>
Commit-Queue: Esmael El-Moslimany <aee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568708}

chrome/browser/resources/md_bookmarks/item.html

@@ -56,6 +56,10 @@
       .more-vert-button {
         -webkit-margin-end: 12px;
       }
+
+      :host(:focus) {
+        z-index: 1;
+      }
     </style>
     <div id="icon"></div>
     <div id="website-title" class="elided-text" title="[[item_.title]]">