gecko: unbreak with more strict regex(3) on FreeBSD 13

In file included from ../.build/dom/workers/Unified_cpp_dom_workers0.cpp:11:
dom/workers/ChromeWorkerScope.cpp:56:10: error: use of undeclared identifier 'JS_InitCTypesClass'

if (!JS_InitCTypesClass(aCx, aGlobal) ||
     ^

dom/workers/ChromeWorkerScope.cpp:61:18: error: unknown type name 'JSCTypesCallbacks'

static const JSCTypesCallbacks callbacks = {
             ^

PR: 233453
Reported by: kevans