Bug with resizing

[christiemolloy]

[High Priority] With the new resize feature we encountered a bug where the user isn’t able to go down to the very last line of code when there is a lot of code in the editor.

Steps to reproduce:

1. HTML/CSS - Module 1 (Building Blocks of PatternFly)
2. Resize the iframe a few times

[Moderate Priority] When the user resizes the frame (e.g. they click on the black bar and then pull down), if they pull down too fast and their cursor leaves the area of the black bar, then the resizing will stop, which users reported as “very jarring”.

cc: @gsoria