Update the `CodeEditorControl`'s `codemirror` deferred to be set before calling the parent class's `initialize` method. Since the `ready` method may be called directly by `initialize` it may be too late to add a new `Deferred` to the control's `deferred` property after calling the base control class's `initialize`.
Amends [41958].
See #41897.
Built from https://develop.svn.wordpress.org/trunk@41960
git-svn-id: http://core.svn.wordpress.org/trunk@41794 1a063a9b-81f0-0310-95a4-ce76da25c4cd
1f735509af