Provide BC typehinting for TableSchema.

composer.json

@@ -42,6 +42,7 @@
             "src/Core/functions.php",
             "src/Collection/functions.php",
             "src/I18n/functions.php",
+            "src/Database/backwards_compat.php",
             "src/Http/backwards_compat.php",
             "src/Utility/bootstrap.php"
         ]

src/Database/backwards_compat.php

@@ -0,0 +1,3 @@
+<?php
+// Ensure backwards compat aliases exists.
+class_exists('Cake\Database\Schema\Table');