Merge 142759

Source/WebCore/svg/properties/SVGPathSegListPropertyTearOff.cpp

Index: Source/WebCore/svg/properties/SVGPathSegListPropertyTearOff.cpp
===================================================================
--- Source/WebCore/svg/properties/SVGPathSegListPropertyTearOff.cpp	(revision 143078)
+++ Source/WebCore/svg/properties/SVGPathSegListPropertyTearOff.cpp	(working copy)
@@ -70,7 +70,7 @@
     return static_cast<SVGPathElement*>(contextElement);
 }
 
-void SVGPathSegListPropertyTearOff::processIncomingListItemValue(const ListItemType& newItem, unsigned* indexToModify)
+bool SVGPathSegListPropertyTearOff::processIncomingListItemValue(const ListItemType& newItem, unsigned* indexToModify)
 {
     SVGPathSegWithContext* newItemWithContext = static_cast<SVGPathSegWithContext*>(newItem.get());
     SVGAnimatedProperty* animatedPropertyOfItem = newItemWithContext->animatedProperty();
@@ -79,29 +79,38 @@
     newItemWithContext->setContextAndRole(contextElement(), m_pathSegRole);
 
     if (!animatedPropertyOfItem)
-        return;
+        return true;
 
     // newItem belongs to a SVGPathElement, but its associated SVGAnimatedProperty is not an animated list tear off.
     // (for example: "pathElement.pathSegList.appendItem(pathElement.createSVGPathSegClosepath())")
     if (!animatedPropertyOfItem->isAnimatedListTearOff())
-        return;
+        return true;
 
     // Spec: If newItem is already in a list, it is removed from its previous list before it is inserted into this list.
     // 'newItem' is already living in another list. If it's not our list, synchronize the other lists wrappers after the removal.
     bool livesInOtherList = animatedPropertyOfItem != m_animatedProperty;
-    int removedIndex = static_cast<SVGAnimatedPathSegListPropertyTearOff*>(animatedPropertyOfItem)->removeItemFromList(newItem.get(), livesInOtherList);
-    ASSERT(removedIndex != -1);
+    SVGAnimatedPathSegListPropertyTearOff* propertyTearOff = static_cast<SVGAnimatedPathSegListPropertyTearOff*>(animatedPropertyOfItem);
+    int indexToRemove = propertyTearOff->findItem(newItem.get());
+    ASSERT(indexToRemove != -1);
 
+    // Do not remove newItem if already in this list at the target index.
+    if (!livesInOtherList && indexToModify && static_cast<unsigned>(indexToRemove) == *indexToModify)
+        return false;
+
+    propertyTearOff->removeItemFromList(indexToRemove, livesInOtherList);
+
     if (!indexToModify)
-        return;
+        return true;
 
     // If the item lived in our list, adjust the insertion index.
     if (!livesInOtherList) {
         unsigned& index = *indexToModify;
         // Spec: If the item is already in this list, note that the index of the item to (replace|insert before) is before the removal of the item.
-        if (static_cast<unsigned>(removedIndex) < index)
+        if (static_cast<unsigned>(indexToRemove) < index)
             --index;
     }
+
+    return true;
 }
 
 }