Fix image tests that make faulty assumptions about lifecycle of image provider (#50297)
Fix image tests that make faulty assumptions about lifecycle of image provider (#50297)


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