remove duplicate canvaskit.js files (#1895)
remove duplicate canvaskit.js files (#1895)

* remove duplicate canvaskit.js files

This is a workaround for #1860 until https://github.com/flutter/engine/pull/26059
lands or we can switch to the HTML renderer in dart-services

* simplify removeCanvaskit function
dart-lang/dart-pad,dart-lang/dart-pad,dart-lang/dart-pad,dart-lang/dart-pad