Fix edit mode handling for markdown cells
Fix edit mode handling for markdown cells

jupyter/jupyter-js-notebook,blink1073/jupyter-js-notebook,blink1073/jupyter-js-notebook,blink1073/jupyter-js-notebook,blink1073/jupyter-js-notebook,jupyter/jupyter-js-notebook,jupyter/jupyter-js-notebook,jupyter/jupyter-js-notebook,blink1073/jupyter-js-notebook,jupyter/jupyter-js-notebook