Change Details

The `value` methods are usually very expensive, because they create new #Wikibase-DataModel-JavaScript objects from what's currently in the edit window(s) on screen. This is usually done for two purposes: 1. `isInitialValue` checks if the user changed something and the save button should be enabled. This is {T124786}. 2. `stopEditing` stores the changed value. Neither of this requires the `value` method, when done properly. When all such usages of a `value` method are removed, the method should be removed.