WebglNodeImageProgram nodes use wrong images after deleting a node

Deleting a node other than the last added node can cause other nodes to display wrong image.

I made a jsfiddle demostrating this issue:
https://jsfiddle.net/40v7c2vs/1/

You can see the issue when you click "delete1" button, which deletes node1 but node2 image changes to node1 image. If you click "delete2" it works correctly because node2 is added after node1.

Start by reproducing the behavior in the linked jsfiddle, focusing on WebglNodeImageProgram after deleting node1. Trace how node deletion affects image assignment, and consider the issue done when deleting a non-last node leaves every remaining node displaying its original image, while deleting node2 still works correctly.

Written by the indexing model from the issue text.