Add test for add-, get-, and removeChildAt to displayObjectContainer.js
Add test for add-, get-, and removeChildAt to displayObjectContainer.js

tschneidereit/shumway,yurydelendik/shumway,tschneidereit/shumway,mozilla/shumway,yurydelendik/shumway,tschneidereit/shumway,mozilla/shumway,mbebenita/shumway,mozilla/shumway,yurydelendik/shumway,mozilla/shumway,mozilla/shumway,mbebenita/shumway,tschneidereit/shumway,tschneidereit/shumway,yurydelendik/shumway,tschneidereit/shumway,yurydelendik/shumway,mozilla/shumway,yurydelendik/shumway,mbebenita/shumway,yurydelendik/shumway,mbebenita/shumway,yurydelendik/shumway,mozilla/shumway,tschneidereit/shumway,mbebenita/shumway,mbebenita/shumway,mozilla/shumway,tschneidereit/shumway,mbebenita/shumway,mbebenita/shumway