Remove the no-longer-needed F/I and D/J alias.

Rationale:
Now that our HIR is type clean (yeah!), we no longer have
to conservatively assume F/I and D/J are aliased. This
enables more accurate side effects analysis, with improvements
in all clients, such a LICM.

Refinement:
The HIR is not completely clean between building and SSA.
This refinement takes care of that, with new tests.

BUG=22538329

Change-Id: Id78ff0ff4e325aeebf0022d868937cff73d3a742