Media: Modify escaping used for upload image announcements.

Replaces `esc_js()` with `wp_json_encode()` for escaping the screen reader announcement when a media upload fails. As the code is within a `<script>` tag rather than an inline script handler, the `esc_js()` function would cause special characters to be announced in their HTML encoded form rather than as the character, eg `&` would be announced as `&amp;`.

Follow up to [60263].

Props peterwilsoncc, joedolson.
Fixes #63114.


git-svn-id: https://develop.svn.wordpress.org/trunk@60520 602fd350-edb4-49c9-b593-d223f7449a82

Author: peterwilsoncc

src/wp-admin/async-upload.php

@@ -142,10 +142,10 @@
 	$speak_message = sprintf(
 		/* translators: %s: Name of the file that failed to upload. */
 		__( '%s has failed to upload.' ),
-		esc_js( $_FILES['async-upload']['name'] )
+		$_FILES['async-upload']['name']
 	);
 
-	echo "<script>_.delay(function() {wp.a11y.speak('" . esc_js( $speak_message ) . "');}, 1500);jQuery( 'button#{$button_unique_id}' ).on( 'click', function() {jQuery(this).parents('div.media-item').slideUp(200, function(){jQuery(this).remove();wp.a11y.speak( wp.i18n.__( 'Error dismissed.' ) );jQuery( '#plupload-browse-button' ).trigger( 'focus' );})});</script>\n";
+	echo '<script>_.delay(function() {wp.a11y.speak(' . wp_json_encode( $speak_message ) . ");}, 1500);jQuery( 'button#{$button_unique_id}' ).on( 'click', function() {jQuery(this).parents('div.media-item').slideUp(200, function(){jQuery(this).remove();wp.a11y.speak( wp.i18n.__( 'Error dismissed.' ) );jQuery( '#plupload-browse-button' ).trigger( 'focus' );})});</script>\n";
 	exit;
 }