Update scroll position when opening from command line with line se lection

Attempt to fix #4780.  

The event listener solution is probably hacky.  I mostly don't quite know when the DisplayBuffer is fully "initialized"/has a height, width, etc.  As of right now if I attempt to call @scrollToCursorPosition() in TextEditor's constructor (at say line 105), the DisplayBuffer has no size information when it gets to scrollToScreenRange() and no scrolling occurs.