Slightly related to this, insomniac games decided a few years ago to move their dev environment to web tools. They found that web just doesn't cut it on the scale needed for a AAA game. In GDC they gave a talk about it the slides can be found here:
https://deplinenoise.wordpress.co...-insomniacs-web-tools-postmortem/
Tl;dr is that you can do such things in web but you need to approach it like you would a native app if you want things to scale properly. Stick to a single framework, don't chase a moving target (fix browser version), have good rules about code that gets added into production, ...
In such a large codebase (300k lines) you need static semantic checking so a typo doesn't result in a crash and you can refactor without leaving undefined function pointers everywhere.