coverity#1242479 Dereference null return value

Change-Id: Ie9a9a3438408900d4a5e07b50f4e636e06f94026

sfx2/source/view/viewfrm.cxx

@@ -1624,14 +1624,11 @@ void SfxViewFrame::DoAdjustPosSizePixel //! divide on Inner.../Outer...
     }
 }
 
-
-
 bool SfxViewFrameItem::operator==( const SfxPoolItem &rItem ) const
 {
-     return PTR_CAST(SfxViewFrameItem, &rItem)->pFrame== pFrame;
+    return dynamic_cast<const SfxViewFrameItem&>(rItem).pFrame == pFrame;
 }
 
-
 OUString SfxViewFrameItem::GetValueText() const
 {
     return OUString();