Fix https://github.com/google/guice/issues/888.

When Binder.requireExplicitBindings() is in effect, don't allow any
JIT bindings to be created in parent injectors, even JIT bindings that
are normally exempt such as the targets of linked key bindings.
So this is kind of funny... as I was editing this file, I kept getting random failures unrelated to the test I was messing with.  Turns out that the exception messages contained things like:

`at ...configure(JitBindingsTest.java:442) (via ...)`

So whenever I happened to push something onto a line number that ended in 2, tests like this would fail.