Twenty Seventeen: Make `<th>` styling in table block consistent between back end and front end.

Props ianbelanger.
Fixes #46568.
Built from https://develop.svn.wordpress.org/trunk@45051


git-svn-id: http://core.svn.wordpress.org/trunk@44860 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-content/themes/twentyseventeen/assets/css/editor-blocks.css

@@ -674,6 +674,7 @@ table.wp-block-table tr {
 	border-bottom: 1px solid #eee;
 }
 
+table.wp-block-table th,
 table.wp-block-table td {
 	border: 0;
 	padding: 0.4em;

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.2-beta1-45050';
+$wp_version = '5.2-beta1-45051';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.