[IR] Remove scopeId from BreakInstr as well.

* Even though break targets can be pinned statically, I am going
  for consistency with non-local return handling and am using
  DynamicScope signature for identifying the break target.

  This lets us get rid of all scopeId uses from the code.

  scopeId can then be removed from IRStaticScope later on once
  it is clear it is no longer needed for anything else.

* inlining code is currently broken and might potentially resurrect
  scopeId -- to be fixed later.