fix some unit test cases(ink_well_test.dart) bug (#70447)
fix some unit test cases(ink_well_test.dart) bug (#70447)

This change fixes some bugs in ink_well_test.dart.
Hixie/flutter,flutter/flutter,tvolkert/flutter,Hixie/flutter,flutter/flutter,tvolkert/flutter,Hixie/flutter,tvolkert/flutter,tvolkert/flutter,Hixie/flutter,tvolkert/flutter,Hixie/flutter,Hixie/flutter,tvolkert/flutter,flutter/flutter,tvolkert/flutter,flutter/flutter,Hixie/flutter,flutter/flutter,flutter/flutter,Hixie/flutter,Hixie/flutter,flutter/flutter,Hixie/flutter,tvolkert/flutter,tvolkert/flutter,tvolkert/flutter,flutter/flutter,flutter/flutter,flutter/flutter