Revert "[4.5] Fix the ALTER TABLE (#4097)"

This reverts commit 88225282273e0d7c0d933d8cb3e2ca6761feedad.

resources/classes/schema.php

@@ -648,11 +648,6 @@ if (!class_exists('schema')) {
 																$sql_update .= "ALTER TABLE ".$table_name." ADD ".$field['name']." ".$field_type.";\n";
 															}
 														}
-														else {
-															if ($field['exists'] == "false") {
-																$sql_update .= "ALTER TABLE ".$table_name." ADD ".$field['name']["text"]." ".$field_type.";\n";
-															}
-														}
 													}
 												//rename fields where the name has changed
 													if (is_array($field['name'])) {