Return the passed-in argument for Constant, Any.
Update AppendInstrumentation().

Ensure that the arguments pass in to function instrumentation are exactly the same as those of the function (+ return value, if applicable), but that we call GetArgumentValue() to do indirection within the translator if needed.
Teach GetArgumentValue about assertion sites.

Put all of the assertion-site-conditional logic in one place.
Field-indirection regression test.

This is to catch issues we were having in kernel builds with field indirection.