(no bug) Clarify comment in ConstructFieldSetFrame (and fix typo s/list frame/fieldset frame/). comment-only, DONTBUILD

layout/base/nsCSSFrameConstructor.cpp

@@ -3149,7 +3149,7 @@ nsCSSFrameConstructor::ConstructFieldSetFrame(nsFrameConstructorState& aState,
 
   newFrame->AddStateBits(NS_FRAME_MAY_HAVE_GENERATED_CONTENT);
 
-  // our new frame returned is the top frame which is the list frame. 
+  // Our new frame returned is the outer frame, which is the fieldset frame.
   *aNewFrame = newFrame; 
 
   return NS_OK;