label:1.change default value of anchor point.  2.Shadow offset and outline size passed to new Label didn't consider 'contentScaleFactor'
Label:fixed shadow offset didn't consider 'contentScaleFactor'
update test case
update test case.
Merge pull request #5942 from Dhilan007/develop_label2

label: 1) change default value of anchor point to Middle.
2) Shadow offset and outline size passed to new Label consider 'contentScaleFactor'