Bug 1462497 - Part 2: Invalidate the new caret frame in subdocuments, since it will result in a new nsDisplayWrapList being created. r=miko,mstange

nsDisplayListBuilder::DisplayCaret returning true means that we set canSkipWrapList to true, and then we build an nsDisplayWrapList.
We need to make sure we're invalidated for this changing in nesting level to be handled.

MozReview-Commit-ID: 4j3WIJDcHtI

layout/generic/nsSubDocumentFrame.cpp

@@ -462,6 +462,9 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
       if (mPreviousCaret) {
         aBuilder->MarkFrameModifiedDuringBuilding(mPreviousCaret);
       }
+      if (aBuilder->GetCaretFrame()) {
+        aBuilder->MarkFrameModifiedDuringBuilding(aBuilder->GetCaretFrame());
+      }
     }
     mPreviousCaret = aBuilder->GetCaretFrame();
   }