Fix broken editor rendering after changing font size on guest portals

[as-cii]

Fixes #174

When editor styles change, Atom notifies only editor components that are attached to the DOM at the moment of the change. Thus, if the element we are about to add had already been rendered, we will preemptively clear all its styling information to ensure it will render correctly even if some styles changed while it was not attached to the DOM.

This is admittedly something that we should have better support for in core, but this workaround should be an okay stopgap measure.

/cc: @nathansobo @jasonrudolph

[nathansobo]

Does the TextEditorRegistry support this curretly?

[as-cii]

I don't think so. Notifications of style updates come straight from AtomEnvironment by calling a static method on TextEditorComponent named didUpdateStyles. That method consults a Set of attached components and, for each of them, calls the didUpdateStyles instance method.

I guess one way of fixing that would be to call didUpdateStyles on every created TextEditorComponent, making sure we delete those components whose editor has been destroyed.

[nathansobo]

I guess one way of fixing that would be to call didUpdateStyles on every created TextEditorComponent, making sure we delete those components whose editor has been destroyed.

Ah, except that could lead to leaks of editors that package authors forget to explicitly destroy. For a solution in core, what if we maintained a static field on the constructor with an incrementing style update counter. When an editor gets reattached, we could compare its count with the constructors and force an update if we see that we're out of date.