This removes the parentHandle argument from the internal calling convention.
It was formerly used to implment coroutines.
Now that coroutines have been removed, it is no longer necessary.
Make sure that if a package initializer cannot be run, later package
initializers won't try to access any global variables touched by the
uninterpretable package initializer.
Previously, a package initializer that could not be reverted correctly
would be called at runtime. But the initializer would be called in the
wrong order: after later packages are initialized.
This commit fixes this oversight and adds a test to verify the new
behavior.
