fastReplace property
This option is useful when you have a transparent layer: rather than
keeping the old layer visible when zooming (resulting in both layers
being temporarily visible), the old layer is removed as quickly as
possible when this is set to true (default false).
This option is likely to cause some flickering of the transparent layer,
most noticeable when using pinch-to-zoom. It's best used with maps that
have interactive set to false, and zoom using buttons that call
MapController.move().
When set to true, the tileFadeIn* options will be ignored.
Implementation
final bool fastReplace;