Remove focus highlight on sample WebView

Disable the default focus highlight on the WebView in the
RotaryPlayground.

Test: use rotary to focus a link in the sample WebView
Bug: 173152508
Change-Id: I12adb7de0f144d4b82df10d2298b9b6cccef1e27
diff --git a/RotaryPlayground/res/layout/rotary_web_view.xml b/RotaryPlayground/res/layout/rotary_web_view.xml
index 7995dc6..6cdc5dd 100644
--- a/RotaryPlayground/res/layout/rotary_web_view.xml
+++ b/RotaryPlayground/res/layout/rotary_web_view.xml
@@ -51,7 +51,8 @@
             android:id="@+id/web_view"
             android:layout_width="match_parent"
             android:layout_height="0dp"
-            android:layout_weight="1" />
+            android:layout_weight="1"
+            android:defaultFocusHighlightEnabled="false"/>
 
         <Button
             android:id="@+id/bottom_button"