Check if hiddenTextarea is in current body

In situations where the document.body was replaced, the check if hiddenTextarea.parentNode === null would return false even if in fact the new document.body had no current hiddenTextarea, thus requiring a new one to be appended. The new logic checks if !document.body.contains(hiddenTextarea), which should account for the current document.body.

See here for more details Andarist#292

Author: leosullivan1

src/calculateNodeHeight.ts

@@ -33,7 +33,7 @@ export default function calculateNodeHeight(
     forceHiddenStyles(hiddenTextarea);
   }
 
-  if (hiddenTextarea.parentNode === null) {
+  if (!document.body.contains(hiddenTextarea)) {
     document.body.appendChild(hiddenTextarea);
   }