Currently the ImageFilterLayer will register its bounds as a readback layer in the DiffContext. This could potentially expand the dirty regions of some nearby layers. After a long discussion with @knopp we believe that this extra readback region processing is not necessary for ImageFilterLayer so the registration of the readback region should be removed.

See https://github.com/flutter/engine/blob/221623d2bb9798411c170d92d69009e0d3b4d435/flow/layers/image_filter_layer.cc#L44