remove obsolete todo

Author: Nicolas Laurent

src/main/java/org/truffleruby/core/array/ArrayAppendOneNode.java

@@ -81,7 +81,6 @@ protected DynamicObject appendOneGeneralizeNonMutable(DynamicObject array, Objec
         final int newCapacity = newSize > oldCapacity
                 ? ArrayUtils.capacityForOneMore(getContext(), oldCapacity)
                 : oldCapacity;
-        // TODO (norswap, 03 Apr 2020): this is a performance warning (inlining a virtual call)
         final Object newStore = currentStores.allocateForNewValue(currentStore, value, newCapacity);
         currentStores.copyContents(currentStore, 0, newStore, 0, oldSize);
         propagateSharingNode.executePropagate(array, value);