[TIMOB-8881] iOS: scrollView - contentWidth and contentHeight only respond to "auto" not Ti.UI.SIZE

scrollView.contentWidth only responds to "auto" and not Ti.UI.SIZE as you would expect with the composite layout changes. This creates an inconsistent experience for developers.

Steps to reproduce:

Step 1: run the code below Step 2: notice that the contentWidth is set to "auto" and is resizing as it should Step 3: replace "auto" with Ti.UI.SIZE Step 4: run the code again Step 5: notice that the scrollView does not scroll. This means that the contentWidth does not resize as you would expect it to with Ti.UI.SIZE

var win = Ti.UI.createWindow({backgroundColor:'white'});
win.open();
 
var scrollView = Ti.UI.createScrollView({
    contentWidth: 'auto',
    // contentWidth: Ti.UI.SIZE,
    backgroundColor: 'black',
    layout: 'horizontal'
});
win.add(scrollView);
 
for(var i = 0, j = 20; i < j; i++){
    scrollView.add(Ti.UI.createView({
        backgroundColor: 'red',
        width: 100,
        height: 400,
        left: 40
    }));
}