Fixed a bug in CodeMirror component lifecycle

[jbeard4]

What I expect to happen:

• first componentWillUpdate is called, such that old and new props are different
• then render() is called with the new props, if componentShouldUpdate is true.

What actually happens:

• first render() is called with the new props.
• then componentWillUpdate is called such that old and new props are the same.

This is because debounce is deferring execution of
componentWillReceiveProps, thus breaking react component lifecycle
(which is described here:
https://busypeoples.github.io/post/react-component-lifecycle/).

[scniro]

@jbeard4 This library is pretty much abandoned. Have you've glimpsed at the plethora of issues? I wrote react-codemirror2 and have been actively maintaining it because of the frustrations I've encountered here. Not to mention the lack of tests, heavy dependencies, ancient documentation, etc. I am shocked people are still grasping on to this library...