Splitting a way doesn't redraw mapcss styled nodes to 'connected' state

[AndrewBuck]

Note for context: This bug was discovered during the course of investigating ticket #7935. However, having fixed that parse error in my stylesheet I still get this issue with the new stylesheet as well.

When splitting a way in JOSM, the node where the split happened is not changed into a 'connection' node and is just left as a normal node. Disabling and re-enabling the paint style redraws the node correctly as a node:connection style node. The same behaviour is exhibited in reverse, if a way is combined into one piece, the connection node is not redrawn until the stylesheet is disabled and re-enabled.

[bastiK]

In 5552/josm:

fixed #7941 - Splitting a way doesn't redraw mapcss styled nodes to 'connected' state