--- a/layout/generic/nsBlockFrame.cpp
+++ b/layout/generic/nsBlockFrame.cpp
@@ -5354,24 +5354,26 @@ nsBlockInFlowLineIterator::nsBlockInFlow
     // rline_end. So we can safely increment it (i.e. move it to one line
     // earlier) to start searching there.
     ++rline;
     while (line != line_end || rline != rline_end) {
       if (line != line_end) {
         if (line->Contains(child)) {
           *aFoundValidLine = true;
           mLine = line;
+          aFrame->SetLineCursor(line.get());
           return;
         }
         ++line;
       }
       if (rline != rline_end) {
         if (rline->Contains(child)) {
           *aFoundValidLine = true;
           mLine = rline;
+          aFrame->SetLineCursor(rline.get());
           return;
         }
         ++rline;
       }
     }
     // Didn't find the line
   }
 
@@ -6519,19 +6521,18 @@ void nsBlockFrame::ClearLineCursor()
 }
 
 void nsBlockFrame::SetupLineCursor()
 {
   if (GetStateBits() & NS_BLOCK_HAS_LINE_CURSOR
       || mLines.empty()) {
     return;
   }
-   
-  Properties().Set(LineCursorProperty(), mLines.front());
-  AddStateBits(NS_BLOCK_HAS_LINE_CURSOR);
+
+  SetLineCursor(mLines.front());
 }
 
 nsLineBox* nsBlockFrame::GetFirstLineContaining(nscoord y)
 {
   if (!(GetStateBits() & NS_BLOCK_HAS_LINE_CURSOR)) {
     return nullptr;
   }
 
@@ -6549,17 +6550,17 @@ nsLineBox* nsBlockFrame::GetFirstLineCon
   }
   while ((cursorArea.IsEmpty() || cursorArea.YMost() <= y)
          && cursor != mLines.back()) {
     cursor = cursor.next();
     cursorArea = cursor->GetVisualOverflowArea();
   }
 
   if (cursor.get() != property) {
-    props.Set(LineCursorProperty(), cursor.get());
+    SetLineCursor(cursor.get());
   }
 
   return cursor.get();
 }
 
 /* virtual */ void
 nsBlockFrame::ChildIsDirty(nsIFrame* aChild)
 {

--- a/layout/generic/nsBlockFrame.h
+++ b/layout/generic/nsBlockFrame.h
@@ -372,16 +372,20 @@ protected:
   }
 #endif
 
   NS_DECLARE_FRAME_PROPERTY(LineCursorProperty, nullptr)
   nsLineBox* GetLineCursor() {
     return (GetStateBits() & NS_BLOCK_HAS_LINE_CURSOR) ?
       static_cast<nsLineBox*>(Properties().Get(LineCursorProperty())) : nullptr;
   }
+  void SetLineCursor(nsLineBox* aCursor) {
+    Properties().Set(LineCursorProperty(), aCursor);
+    AddStateBits(NS_BLOCK_HAS_LINE_CURSOR);
+  }
 
   nsLineBox* NewLineBox(nsIFrame* aFrame, bool aIsBlock) {
     return NS_NewLineBox(PresContext()->PresShell(), aFrame, aIsBlock);
   }
   nsLineBox* NewLineBox(nsLineBox* aFromLine, nsIFrame* aFrame, int32_t aCount) {
     return NS_NewLineBox(PresContext()->PresShell(), aFromLine, aFrame, aCount);
   }
   void FreeLineBox(nsLineBox* aLine) {