свойство backingStorePixelRatio
Устарело: всегда возвращает 1.0
Реализация
@deprecated double get backingStorePixelRatio => 1.0;
© 2012 the Dart project authors
Licensed under the BSD 3-Clause "New" or "Revised" License.
https://api.dart.dev/stable/2.19.6/dart-html/CanvasRenderingContext2D/backingStorePixelRatio.html
