Check if registerScratchCanvas is defined before calling it
Check if registerScratchCanvas is defined before calling it

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