Placeholder for https://github.com/jenkinsci/jenkins/pull/4046

Currently, plugins cannot cleanly provide a custom onBlur handler for their codemirror textareas, because it is being overridden in core. This has been the case since 4e48eaa, but it does not look like that side-effect has been intentional.

(Plugins could work around this in a hackish way, by adding })// at the end of their codemirror-config.)