[TIMOB-12189] iOS: imageWithRoundedCorner() makes opaque corners instead of transparent corners

var win1=Ti.UI.createWindow({backgroundColor:'blue'});

var RoundedFile;

var PhoneDataDirectory=Ti.Filesystem.getFile(Ti.Filesystem.applicationDataDirectory);
if (! PhoneDataDirectory.exists())
  PhoneDataDirectory.createDirectory();

var Label1=Ti.UI.createLabel({top:2, left:2, text:'M and Ms',
                              color:'orange',
                              backgroundColor:'black'});
win1.add(Label1);

function Step1()
{
  Ti.Media.takeScreenshot(ContinueStep1);
}
var Step1Button=Ti.UI.createButton({title:'Step 1', left:5, top:'50%'});
win1.add(Step1Button);
Step1Button.addEventListener('click',Step1);

function ContinueStep1(ScreenShot)
{
  var ScreenBlob=ScreenShot.media;
  var SectionBlob=ScreenBlob.imageAsCropped({x:0,
                                             y:25,
                                             width:90,
                                             height:50
                                            });
  var Rounded=SectionBlob.imageWithRoundedCorner(20);
  RoundedFile=Ti.Filesystem.getFile(PhoneDataDirectory.nativePath,'Rounded.png');
  RoundedFile.write(Rounded);
  Step1Button.title='Done';
}

function Step2()
{
  var RoundedImage=Ti.UI.createImageView({image:RoundedFile,
                                          bottom:2, right:2,
                                          width:Ti.UI.SIZE,
                                          height:Ti.UI.SIZE });
  win1.add(RoundedImage);
}
var Step2Button=Ti.UI.createButton({title:'Step 2', left:165, top:'50%'});
win1.add(Step2Button);
Step2Button.addEventListener('click',Step2);

win1.open();