Embeds: Adjust the iframe title attribute for improved accessibility.

Changes the title attribute from `Embedded WordPress Post` to `"Post name" — site title`.

Props ramiy.
Fixes #35804.

git-svn-id: https://develop.svn.wordpress.org/trunk@36873 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/embed.php

@@ -490,7 +490,14 @@ JS;
 		esc_url( $embed_url ),
 		absint( $width ),
 		absint( $height ),
-		esc_attr__( 'Embedded WordPress Post' )
+		esc_attr(
+			sprintf(
+				/* translators: 1: post title, 2: site name */
+				__( '“%1$s” — %2$s' ),
+				get_the_title( $post ),
+				get_bloginfo( 'name' )
+			)
+		)
 	);
 
 	/**