Editor: Add Media should be a button

Props afercia.
Fixes #32969.

Built from https://develop.svn.wordpress.org/trunk@33298


git-svn-id: http://core.svn.wordpress.org/trunk@33270 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/media.php

@@ -552,10 +552,9 @@ function media_buttons($editor_id = 'content') {
 	$img = '<span class="wp-media-buttons-icon"></span> ';
 
 	$id_attribute = $instance === 1 ? ' id="insert-media-button"' : '';
-	printf( '<a href="#"%s class="button insert-media add_media" data-editor="%s" title="%s">%s</a>',
+	printf( '<button type="button"%s class="button insert-media add_media" data-editor="%s">%s</button>',
 		$id_attribute,
 		esc_attr( $editor_id ),
-		esc_attr__( 'Add Media' ),
 		$img . __( 'Add Media' )
 	);
 	/**

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.3-beta3-33297';
+$wp_version = '4.3-beta3-33298';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.