Steps to reproduce:
1.Go to this page:http://en.wikipedia.beta.wmflabs.org/w/index.php?title=User:RYasmeen_%28WMF%29/sandbox&redirect=no&veaction=edit
2.Place your cursor just before the text "content" and drag your selection over the text covering the reflist
Observed Result:
As soon as you select the reflist it throws the following error and pressing delete wont delete the all content
Error: offset was inside an ignoreChildren node