Bug 1679706 - Fix an obvious typo in nsPrintJob::GetIsEmpty().

This will get tested when the front-end uses the value.

Differential Revision: https://phabricator.services.mozilla.com/D98575

layout/printing/nsPrintJob.cpp

@@ -883,7 +883,7 @@ bool nsPrintJob::GetIsEmpty() const {
   if (numSheets > 1) {
     return false;
   }
-  return seqFrame->GetPagesInFirstSheet() > 0;
+  return !seqFrame->GetPagesInFirstSheet();
 }
 
 int32_t nsPrintJob::GetPrintPreviewNumSheets() const {