Bug 1648064 - Disable lazy loading for print documents. r=hiro

This, along with the previous patches, allow lazy-loaded images to show
up in print, even if they haven't been loaded otherwise.

Differential Revision: https://phabricator.services.mozilla.com/D81780

dom/html/HTMLImageElement.cpp

@@ -1256,7 +1256,10 @@ void HTMLImageElement::SetLazyLoading() {
 
   // If scripting is disabled don't do lazy load.
   // https://whatpr.org/html/3752/images.html#updating-the-image-data
-  if (!OwnerDoc()->IsScriptEnabled()) {
+  //
+  // Same for printing.
+  Document* doc = OwnerDoc();
+  if (!doc->IsScriptEnabled() || doc->IsStaticDocument()) {
     return;
   }