tdf#88360: sw: fix crash on closing help in Navigator window

SwContentTree::pActiveShell is not cleared because of a check that the
shell exists, which is only done in the special case bIsConstant.

* at most one of bIsActive or bIsConstant is true
* the only place that calls SetActiveShell() if bIsConstant is true
  already checks this condition

So remove the unnecessary check from SetActiveShell()

Change-Id: Id3b3b98bd38303b5afc529cc8be669872bd354b7

sw/source/uibase/utlui/content.cxx

@@ -2219,8 +2219,6 @@ void SwContentTree::SetActiveShell(SwWrtShell* pSh)
         Clear();
     }
     else if(bIsConstant)
-    {
-        if(!lcl_FindShell(pActiveShell))
     {
         if (pActiveShell)
             EndListening(*pActiveShell->GetView().GetDocShell());
@@ -2229,7 +2227,6 @@ void SwContentTree::SetActiveShell(SwWrtShell* pSh)
         bIsConstant = false;
         bClear = true;
     }
-    }
     // Only if it is the active view, the array will be deleted and
     // the screen filled new.
     if(bIsActive && bClear)