* Fix "app-init" injection
The way we were injecting variables into the `app-init.js` bundle was
accidentally overwriting the bundle output with the raw `app-init.js`
source file. This is a problem because the bundling process handles a
lot of things we care about like source maps, polyfills and other
necessary Babel transformations, environment variable injection, and
minification.
Instead of using string replacement to inject variables, we are now
using environment variables. The old string replacement strategy has
been removed, and the `app-init.js` module is now generated using the
same process as our other bundles.
A new option, "extraEnvironmentVariables", was added to allow us to
inject environment variables specifically for this bundle.
* Add check to ensure APPLY_LAVAMOAT is set
This reverts commit f09ab88891, reversing
changes made to effc761e0e.
This is being temporarily reverted to make it easier to release an
urgent fix for v10.15.1.
David Walsh
Mark Stacey
Jyoti Puri
Dan Miller