Use your own editor instead of web editors.
Edit any* editable web content with a text editor.
This extension requires a native component for it to work. You can download and install the additional component at https://github.com/hnry/kindred
This extension is open source and the source code can be at that link as well.
It also requires knowledge of DOM inspection and jQuery style selectors as well as some basic regular expression. This is for setting up rules so kindred knows how to bind to certain websites you specify.
* The code is in place to support any editable element or web component. However it's impossible for me to go searching for every 'specialized' case. Right now it has support for simple input's and textarea's as well as sites that use CodeMirror.