Previously, I used a shell script to extract modification date ranges
from the Git history, but that was complicated and unreliable, so now
every file just gets the same year range in its copyright header. If
someone needs to know when a specific file was modified and by whom,
they can look at the Git history themselves; no need to include it
redundantly in the header.
This test covers the case where a local stack slot is first used to
store an object reference and later to store a subroutine return
address. Unfortunately, this confuses the VM's stack mapping code;
I'll be working on a fix for that next.
The new test requires generating bytecode from scratch, since there's
no reliable way to get javac to generate the code we want. Since we
already had primitive bytecode construction code in Proxy.java, I
factored it out so we can reuse it in Subroutine.java.
