check existence of task files (#10959)
check existence of task files (#10959)


cbracken/flutter,tvolkert/flutter,tvolkert/flutter,tvolkert/flutter,cbracken/flutter,Hixie/flutter,tvolkert/flutter,tvolkert/flutter,cbracken/flutter,flutter/flutter,Hixie/flutter,flutter/flutter,turnidge/flutter,turnidge/flutter,flutter/flutter,tvolkert/flutter,Hixie/flutter,tvolkert/flutter,turnidge/flutter,cbracken/flutter,Hixie/flutter,flutter/flutter,flutter/flutter,tvolkert/flutter,cbracken/flutter,Hixie/flutter,turnidge/flutter,cbracken/flutter,tvolkert/flutter,flutter/flutter,cbracken/flutter,tvolkert/flutter,flutter/flutter,Hixie/flutter,turnidge/flutter,Hixie/flutter,Hixie/flutter,Hixie/flutter,flutter/flutter,cbracken/flutter,cbracken/flutter,cbracken/flutter,flutter/flutter,flutter/flutter,Hixie/flutter