Whether this object has been disposed or is currently disposing.
This is equivalent to:
object.isDisposed || object.isDisposing
Deprecated: 1.9.0 To be removed: 2.0.0
This was intended as a convenience method to be used to guard against APIs being called after disposal has started. Consumers should now use isOrWillBeDisposed instead because it also returns true when this instance is in the "awaiting disposal" state that is entered as soon as dispose is called, whereas this getter does not return true until disposal has actually started.
@deprecated bool get isDisposedOrDisposing => isDisposed || isDisposing;