Bug 1827445: fixing problem table_exists() call

Making it a db_table_exists() call instead

behatnotneeded

Change-Id: I5206657a7e76a96dbe878147e07d42a241790764
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>

htdocs/webservice/lib.php

@@ -446,7 +446,7 @@ function webservice_connection_definitions() {
         $plugins[$plugin]['notinstalled'] = array();
     }
     foreach (array_keys($plugins) as $plugin) {
-        if (table_exists(new XMLDBTable($plugin . '_installed'))) {
+        if (db_table_exists($plugin . '_installed')) {
             if ($installed = plugins_installed($plugin, true)) {
                 foreach ($installed as $i) {
                     $key = $i->name;