Index: wp-includes/customize/class-wp-customize-site-icon-control.php
===================================================================
--- wp-includes/customize/class-wp-customize-site-icon-control.php	(revision 37631)
+++ wp-includes/customize/class-wp-customize-site-icon-control.php	(working copy)
@@ -63,7 +63,7 @@
 			<div class="attachment-media-view">
 				<div class="site-icon-preview">
 					<div class="favicon-preview">
-						<img src="<?php echo esc_url( admin_url( 'images/browser.png' ) ); ?>" class="browser-preview" width="182" alt="" />
+						<img src="<?php echo esc_url( admin_url( 'images/'.( is_rtl() ? 'browser-rtl.png' : 'browser.png' ) ) ); ?>" class="browser-preview" width="182" alt="" />
 
 						<div class="favicon">
 							<img id="preview-favicon" src="{{ data.attachment.sizes.full.url }}" alt="<?php esc_attr_e( 'Preview as a browser icon' ); ?>"/>
Index: wp-includes/media-template.php
===================================================================
--- wp-includes/media-template.php	(revision 37631)
+++ wp-includes/media-template.php	(working copy)
@@ -1240,7 +1240,7 @@
 		<h2><?php _e( 'Preview' ); ?></h2>
 		<strong aria-hidden="true"><?php _e( 'As a browser icon' ); ?></strong>
 		<div class="favicon-preview">
-			<img src="images/browser.png" class="browser-preview" width="182" height="" alt="" />
+			<img src="images/<?php echo is_rtl() ? 'browser-rtl.png' : 'browser.png' ?>" class="browser-preview" width="182" height="" alt="" />
 
 			<div class="favicon">
 				<img id="preview-favicon" src="{{ data.url }}" alt="<?php esc_attr_e( 'Preview as a browser icon' ); ?>"/>