src: replace handle dereference with ContainerOf

this was influenced by #32269

PR-URL: #32298
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

src/process_wrap.cc

@@ -292,8 +292,7 @@ class ProcessWrap : public HandleWrap {
   static void OnExit(uv_process_t* handle,
                      int64_t exit_status,
                      int term_signal) {
-    ProcessWrap* wrap = static_cast<ProcessWrap*>(handle->data);
-    CHECK_NOT_NULL(wrap);
+    ProcessWrap* wrap = ContainerOf(&ProcessWrap::process_, handle);
     CHECK_EQ(&wrap->process_, handle);
 
     Environment* env = wrap->env();