GetCalleeAndThisFromEnvironment treated a binding as initialized when
its value slot was not <empty>. Declarative bindings do not encode TDZ
in that slot, though: uninitialized bindings keep a separate initialized
flag and their value starts as undefined.
That let the first slow-path TDZ failure populate the environment cache,
then a second call at the same site reused the cached coordinate and
turned the required ReferenceError into a TypeError from calling
undefined.
Check Binding.initialized in the asm fast path instead and cover the
cached second-hit case with a regression test.