tdf#100756 slowdown in manipulating spreadsheet via UNO

regression from
    commit 5bce3290
    SfxHint: convert home-grown RTTI to normal C++ RTTI

the cost does seem in this case to be mostly the dynamic_cast, but since
we don't need it anymore, just remove it

Change-Id: Icbf51b89c036b86cfb3e4c2a827228ccf25bb3a6
Reviewed-on: https://gerrit.libreoffice.org/54899Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

sc/source/ui/unoobj/textuno.cxx

@@ -987,14 +987,6 @@ void ScCellTextData::UpdateData()
 
 void ScCellTextData::Notify( SfxBroadcaster&, const SfxHint& rHint )
 {
-    if ( dynamic_cast<const ScUpdateRefHint*>(&rHint) )
-    {
-//        const ScUpdateRefHint& rRef = (const ScUpdateRefHint&)rHint;
-
-        //! Ref-Update
-    }
-    else
-    {
     const SfxHintId nId = rHint.GetId();
     if ( nId == SfxHintId::Dying )
     {
@@ -1008,7 +1000,6 @@ void ScCellTextData::Notify( SfxBroadcaster&, const SfxHint& rHint )
         if (!bInUpdate)                         // not for own UpdateData calls
             bDataValid = false;                 // text has to be read from the cell again
     }
-    }
 }
 
 ScCellTextObj::ScCellTextObj(ScDocShell* pDocSh, const ScAddress& rP) :