GetTracker()->GetPrimaryFrameFor(aTableContent, &tableFrame);
mShell->GetPrimaryFrameFor(aTableContent, &tableFrame);
nsSelection::GetTableLayout(nsIContent *aTableContent){  // Get frame for table  nsIFrame *tableFrame = nsnull;  GetTracker()->GetPrimaryFrameFor(aTableContent, &tableFrame);  if (!tableFrame)    return nsnull;  nsITableLayout *tableLayoutObject = nsnull;  CallQueryInterface(tableFrame, &tableLayoutObject);  return tableLayoutObject;}