[IR] Finish up integrating IRFor scope and fixing bugs.

* Break and Non-local return handling now account for IRFor scope.
* Closure cloning handles cloning of IRFor scope.
* Fixed flipped condition in IRBuilder.
* Fixed scope-depth issues for local variables in closures -- this
  needed to be handled in IRClosure after all while accounting for
  IRFor scopes.
* IR runspecs now back at 10E + 3F.

* This following ruby snippets now runs as well:

def foo; yield; end

a = 1
for i in [1,2,3]
  foo {
    p a + i
  }
end