Creating a menu/menubar needs to be synchronous because we need the
ID from the response, but adding stuff *to* menus (and adding menus
to menubars, and menubars to windows) can all be asynchronous.
This dramatically reduces the amount of IPC ping-pong played by
each GUI application during startup.
I measured how long it takes TextEditor to enter the main event loop
and it's over 10% faster here. (Down from ~86ms to ~74ms)
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
