Revert "Fine tunes the content view observers in SC.ScrollView. This prevents additional observers from being added to views that don't support calculatedHeight or calculatedWidth and prevents additional frame observers for being added to collection views, which reduces the duplicate calls to SC.ScrollView's contentViewFrameDidChange."

This reverts commit a7c8c6adb72a3172ad2bfdf4323943ace255f03f.
Keeps the change to SC.StackedView to set calculatedHeight.