Normalize truth value.

We could come across a case where it will not be 1.
Don't redo dead instruction elim on inlinees.

For one, they've already had it done. For two, this doesn't quite
respect deopt boundaries correctly.
Make sure inlined args are always marked as used.
Change ext op API to make JITting them easier.

Now we pass in the memory associated with the current bytecode, so the
JIT will be able to do the same trick.
Merge remote-tracking branch 'origin/master' into moar-jit