SpreadSheet: remove function

Observer is no longer required as PropertySheet is now derived from  PropertyLinkBase and will handle all the link related behavior

src/Mod/Spreadsheet/App/PropertySheet.cpp

@@ -1372,8 +1372,6 @@ void PropertySheet::addDependencies(CellAddress key)
 
             std::string docObjName = docObj->getFullName();
 
-            owner->observeDocument(doc);
-
             documentObjectToCellMap[docObjName].insert(key);
             cellToDocumentObjectMap[key].insert(docObjName);
             ++updateCount;
@@ -1447,7 +1445,6 @@ void PropertySheet::removeDependencies(CellAddress key)
             std::map<std::string, std::set<CellAddress>>::iterator k =
                 documentObjectToCellMap.find(*j);
 
-            // assert(k != documentObjectToCellMap.end());
             if (k != documentObjectToCellMap.end()) {
                 k->second.erase(key);
 

src/Mod/Spreadsheet/App/Sheet.cpp

@@ -1661,33 +1661,6 @@ void Sheet::onDocumentRestored()
     }
 }
 
-/**
- * @brief Create a document observer for this sheet. Used to track changes.
- * @param document document to observer.
- */
-
-void Sheet::observeDocument(Document* document)
-{
-    // observer is no longer required as PropertySheet is now derived from
-    // PropertyLinkBase and will handle all the link related behavior
-#if 1
-    (void)document;
-#else
-    ObserverMap::const_iterator it = observers.find(document->getName());
-
-    if (it != observers.end()) {
-        // An observer already exists, increase reference counter for it
-        it->second->ref();
-    }
-    else {
-        // Create a new observer
-        SheetObserver* observer = new SheetObserver(document, &cells);
-
-        observers[document->getName()] = observer;
-    }
-#endif
-}
-
 void Sheet::renameObjectIdentifiers(const std::map<ObjectIdentifier, ObjectIdentifier>& paths)
 {
     DocumentObject::renameObjectIdentifiers(paths);

src/Mod/Spreadsheet/App/Sheet.h

@@ -232,8 +232,6 @@ public:
 
     boost::signals2::signal<void(int, int)> rowHeightChanged;
 
-    void observeDocument(App::Document* document);
-
     void renameObjectIdentifiers(
         const std::map<App::ObjectIdentifier, App::ObjectIdentifier>& paths) override;