[Pharo-dev] Rubric: spotter with preview leaks some memory

Open fresh image 50536 Open Spotter, enable preview (cmd+p) search for EllipseMorph dive in instance-methods scroll through the list one item after another. open playground evaluate RubTextLine allInstances size. "553896" case 17421 is related to this, but does not fully solves this. please review and comment on that fix, so we can integrate this soon. The problem sometimes remains even with this fix. The memory (instance count of RubTextLine) just grows in the background