Fix: invalid reference in generate-global-assert-wrappers.php

Author: ngyuki

build/scripts/generate-global-assert-wrappers.php

@@ -21,6 +21,9 @@
 namespace PHPUnit\Framework;
 
 use ArrayAccess;
+use Countable;
+use DOMDocument;
+use DOMElement;
 use PHPUnit\Framework\Constraint\Constraint;
 use PHPUnit\Framework\ExpectationFailedException;
 use PHPUnit\Framework\MockObject\Rule\AnyInvokedCount as AnyInvokedCountMatcher;