Coding Standards: Add missing escaping in `Custom_Image_Header::step_…

…2()`.

Follow-up to [4673], [14907].

Props nareshbheda, audrasjb, kebbet.
Fixes #59278.

git-svn-id: https://develop.svn.wordpress.org/trunk@57364 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/class-custom-image-header.php

@@ -934,7 +934,7 @@ public function step_2() {
 	<p class="hide-if-js"><strong><?php _e( 'You need JavaScript to choose a part of the image.' ); ?></strong></p>
 
 	<div id="crop_image" style="position: relative">
-		<img src="<?php echo esc_url( $url ); ?>" id="upload" width="<?php echo $width; ?>" height="<?php echo $height; ?>" alt="" />
+		<img src="<?php echo esc_url( $url ); ?>" id="upload" width="<?php echo esc_attr( $width ); ?>" height="<?php echo esc_attr( $height ); ?>" alt="" />
 	</div>
 
 	<input type="hidden" name="x1" id="x1" value="0" />