Bug 1645339 - Use range-based for with nsTObserverArray in layout/generic. r=tnikkel

Differential Revision: https://phabricator.services.mozilla.com/D79498

layout/generic/nsImageFrame.cpp

@@ -2652,10 +2652,7 @@ void nsImageFrame::IconLoad::Notify(imgIRequest* aRequest, int32_t aType,
                                     imgIContainer::FLAG_HIGH_QUALITY_SCALING);
   }
 
-  nsTObserverArray<nsImageFrame*>::ForwardIterator iter(mIconObservers);
-  nsImageFrame* frame;
-  while (iter.HasMore()) {
-    frame = iter.GetNext();
+  for (nsImageFrame* frame : mIconObservers.ForwardRange()) {
     frame->InvalidateFrame();
   }
 }