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

@@ -987,27 +987,18 @@ void ScCellTextData::UpdateData()
 
 void ScCellTextData::Notify( SfxBroadcaster&, const SfxHint& rHint )
 {
-    if ( dynamic_cast<const ScUpdateRefHint*>(&rHint) )
+    const SfxHintId nId = rHint.GetId();
+    if ( nId == SfxHintId::Dying )
     {
-//        const ScUpdateRefHint& rRef = (const ScUpdateRefHint&)rHint;
+        pDocShell = nullptr;                       // invalid now
 
-        //! Ref-Update
+        DELETEZ( pForwarder );
+        pEditEngine.reset();     // EditEngine uses document's pool
     }
-    else
+    else if ( nId == SfxHintId::DataChanged )
     {
-        const SfxHintId nId = rHint.GetId();
-        if ( nId == SfxHintId::Dying )
-        {
-            pDocShell = nullptr;                       // invalid now
-
-            DELETEZ( pForwarder );
-            pEditEngine.reset();     // EditEngine uses document's pool
-        }
-        else if ( nId == SfxHintId::DataChanged )
-        {
-            if (!bInUpdate)                         // not for own UpdateData calls
-                bDataValid = false;                 // text has to be read from the cell again
-        }
+        if (!bInUpdate)                         // not for own UpdateData calls
+            bDataValid = false;                 // text has to be read from the cell again
     }
 }