[IR] Minor: Renamed variables for consistency.
[IR] Minor: Deleted dead code.
[IR] Inlined useless getSelf(IRScope s) method in IRBuilder.
[IR] Code refactoring in IRBuilder to aid ensure block IR changes.

* Unrelated minor code reorg + whitespace fixes in IRScope.
[IR] Bug fix in IR for returns in loops in begin-ensure blocks.

* This ruby snippet would have only printed 'returning' without
  this fix whereas it should have printed 'returning', 'inner',
  and 'outer'.

* TODO: Are we missing a rubyspec?

def foo
  begin
    i = 1
    while i < 10 do
      begin
        if i == 1
          p 'returning'
          return
        end
      ensure
        p 'inner'
      end
      i += 1
    end
  ensure
    p 'outer'
  end
end

foo
[IR] Added missing cloneForInlining methods to a few instructions

* cloneForInlining is required to inline ensure blocks
  at different sites in the host scope.