Wrong dynamic_cast

EditCharAttrib doesn't inherit from or related to SvxFieldItem
Moreover, we can see lines like this:
const SvxFieldItem* pFieldItem = dynamic_cast<const SvxFieldItem*>(pAttr->GetItem());

Change-Id: I9f5710dc4a9a4e71d31538620a9ddc1dedee063f
Reviewed-on: https://gerrit.libreoffice.org/19575Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

editeng/source/editeng/impedit3.cxx

@@ -3175,7 +3175,7 @@ void ImpEditEngine::Paint( OutputDevice* pOutDev, Rectangle aClipRect, Point aSt
                                 {
                                     const EditCharAttrib* pAttr = pPortion->GetNode()->GetCharAttribs().FindFeature(nIndex);
                                     DBG_ASSERT( pAttr, "Field not found");
-                                    DBG_ASSERT( dynamic_cast< const SvxFieldItem* >( pAttr ) !=  nullptr, "Field of the wrong type! ");
+                                    DBG_ASSERT( dynamic_cast< const EditCharAttribField* >( pAttr ) !=  nullptr, "Field of the wrong type! ");
                                     aText = static_cast<const EditCharAttribField*>(pAttr)->GetFieldValue();
                                     nTextStart = 0;
                                     nTextLen = aText.getLength();
@@ -3523,7 +3523,7 @@ void ImpEditEngine::Paint( OutputDevice* pOutDev, Rectangle aClipRect, Point aSt
                                 {
                                     const EditCharAttrib* pAttr = pPortion->GetNode()->GetCharAttribs().FindFeature(nIndex);
                                     DBG_ASSERT( pAttr, "Field not found" );
-                                    DBG_ASSERT( dynamic_cast< const SvxFieldItem* >( pAttr  ) !=  nullptr, "Wrong type of field!" );
+                                    DBG_ASSERT( dynamic_cast< const EditCharAttribField* >( pAttr  ) !=  nullptr, "Wrong type of field!" );
 
                                     // add a meta file comment if we record to a metafile
                                     if( bMetafileValid )