Firefox shows blank box when changing size of graph.

[KatieWoe]

Device
Jordan
OS
Mac 10.13.6 and 10.14.3
Browser
Firefox
Problem Description
For phetsims/qa#228, phetsims/qa#231, and phetsims/qa#229
When dragging an area box a section to the right briefly disappears. Only seen so far on Mac firefox. Appears on published version. Easier to see in small window or iframe.
Steps to reproduce

1. Go to the iframe of the sim on Mac firefox
2. Select a screen with a draggable area.
3. Make the box as tall as possible
4. Quickly drag this box to the right.
5. Drag back to the left and repeat.

Screenshots
https://drive.google.com/file/d/1uZYxLfvrsSFzeNv9ZL3K7DDs44duocm1/view?usp=sharing

[KatieWoe]

Edit: this is not a CT issue. Sorry, I made this issue right after going through CT and I accidentally added it.

[KatieWoe]

It will also occur to the calculations box if the graph is enlarged downwards

[KatieWoe]

Also seen on Win 7 firefox

[ariel-phet]

This is easiest to reproduce in the "iframe test" but I can reproduce it if I choose the right aspect ratio on Win 7 FF. Seems to be very aspect ratio dependent to reproduce. No issue seen at my normal browser window size.

Only worth fixing if not a ton of effort. Feel free to defer if fixing is more than 2 or so hours.

[jonathanolson]

I had some things that seemed promising but nothing seems to be fixing this. Hopefully Firefox will fix the issue soon! Marking as deferred.

[etwa4650]

Also found in phetsims/qa#318

Video:
https://drive.google.com/open?id=1VoMNideIJRXS5CUBUlPOH3SdmGht009s

[JRomero0613]

This bug is still present in phetsims/qa#380. This was noticed with the iFrame test on Windows 7 on Firefox.