Bug 1587905 - Remove useless variable 'subdocFrame' declaration & assignation r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D48889

--HG--
extra : moz-landing-system : lando

layout/generic/nsFrameSetFrame.cpp

@@ -934,11 +934,10 @@ void nsHTMLFramesetFrame::Reflow(nsPresContext* aPresContext,
     if (firstTime) {
       int32_t childVis;
       nsHTMLFramesetFrame* framesetFrame = do_QueryFrame(child);
-      nsSubDocumentFrame* subdocFrame;
       if (framesetFrame) {
         childVis = framesetFrame->mEdgeVisibility;
         mChildBorderColors[childX] = framesetFrame->mEdgeColors;
-      } else if ((subdocFrame = do_QueryFrame(child))) {
+      } else if (child->IsSubDocumentFrame()) {
         if (eFrameborder_Yes == mChildFrameborder[childX]) {
           childVis = ALL_VIS;
         } else if (eFrameborder_No == mChildFrameborder[childX]) {