The ISOLATE mechanism was originally added to implement the subimage isolation that the ImageView Viewport was implementing, but with the fix for RT-19962 we no longer enforce edge conditions for viewports. This mechanism may no longer be needed if no other code that uses Graphics.drawTexture() needs any sort of edge condition enforcement.

One other factor that may impact whether we can delete this mechanism is whether we want to add edge control attributes to the Image and ImageView nodes.