MD WebUI: change how initial focus works in <dialog>s now that they know about shadow DOM

ui/webui/resources/cr_elements/cr_dialog/cr_dialog.html

Index: ui/webui/resources/cr_elements/cr_dialog/cr_dialog.html
diff --git a/ui/webui/resources/cr_elements/cr_dialog/cr_dialog.html b/ui/webui/resources/cr_elements/cr_dialog/cr_dialog.html
index c793f8dcba6e163c160867c8ffc24f6f5021216e..246aa2bf06dabab43b134b020dac021128ddc805 100644
--- a/ui/webui/resources/cr_elements/cr_dialog/cr_dialog.html
+++ b/ui/webui/resources/cr_elements/cr_dialog/cr_dialog.html
@@ -33,11 +33,11 @@
         border-bottom: 1px solid var(--divider-color);
         display: flex;
         min-height: 52px;
+        outline: none;
       }
 
       :host ::content .title {
         font-size: 123.07%; /* (16px / 13px) * 100 */
-        outline: none;
       }
 
       #close {
@@ -95,7 +95,7 @@
         border-top: 1px solid var(--divider-color);
       }
     </style>
-    <div class="title-container">
+    <div class="title-container" tabindex="-1">
       <content select=".title"></content>
       <paper-icon-button icon="cr:clear" on-tap="cancel" id="close"
           aria-label$="[[closeText]]">