Avoid unnecessary illegal downcasts from SwFrmFmt to SwSectionFmt

Change-Id: I2ca8d57a09b6f8c6d760b5fb6a3d2f94ad22ada3

sw/inc/section.hxx

@@ -291,7 +291,7 @@ class SW_DLLPUBLIC SwSectionFmt
     SAL_DLLPRIVATE void UpdateParent();      // Parent has been changed.
 
 protected:
-    SwSectionFmt( SwSectionFmt* pDrvdFrm, SwDoc *pDoc );
+    SwSectionFmt( SwFrmFmt* pDrvdFrm, SwDoc *pDoc );
    virtual void Modify( const SfxPoolItem* pOld, const SfxPoolItem* pNew ) SAL_OVERRIDE;
 
 public:

sw/source/core/docnode/ndsect.cxx

@@ -504,9 +504,8 @@ SwSection* SwDoc::GetCurrSection( const SwPosition& rPos ) const
 
 SwSectionFmt* SwDoc::MakeSectionFmt( SwSectionFmt *pDerivedFrom )
 {
-    if( !pDerivedFrom )
-        pDerivedFrom = (SwSectionFmt*)mpDfltFrmFmt;
-    SwSectionFmt* pNew = new SwSectionFmt( pDerivedFrom, this );
+    SwSectionFmt* pNew = new SwSectionFmt(
+        pDerivedFrom == 0 ? mpDfltFrmFmt : pDerivedFrom, this );
     mpSectionFmtTbl->push_back( pNew );
     return pNew;
 }

sw/source/core/docnode/section.cxx

@@ -625,7 +625,7 @@ const SwTOXBase* SwSection::GetTOXBase() const
     return pRet;
 }
 
-SwSectionFmt::SwSectionFmt( SwSectionFmt* pDrvdFrm, SwDoc *pDoc )
+SwSectionFmt::SwSectionFmt( SwFrmFmt* pDrvdFrm, SwDoc *pDoc )
     : SwFrmFmt( pDoc->GetAttrPool(), OUString(), pDrvdFrm )
 {
     LockModify();