The goal is to make the viewer node jump less often because each unnecessary
jump feels annoying. Previously, we already had a heuristic that would disable
the jumping if the new viewer location was further away than the old one. Now
the viewer never jumps when it's still visible in the node editor and already to
the right of the node-to-view.
As a byproduct this also fixes an issue where the initial viewer position does
not work properly, because the node does not have known draw-bounds yet.
Pull Request: https://projects.blender.org/blender/blender/pulls/138744
e4e49e1634