* Rewrite Kernel#tap with Ruby
This was good for VM too, but of course my intention is to unblock JIT's inlining of a block over yield
(inlining invokeyield has not been committed though).
* Fix test_settracefunc
About the :tap deletions, the :tap events are actually traced (we already have a TracePoint test for builtin methods),
but it's filtered out by tp.path == "xyzzy" (it became "<internal:kernel>"). We could trace tp.path == "<internal:kernel>"
cases too, but the lineno is impacted by kernel.rb changes and I didn't want to make it fragile for kernel.rb lineno changes.
