Adjust location of canRemoveRefTemps call

canRemoveRefTemps was being called on functions after their nested
functions were inlined. This would cause ref temps to be removed when
they shouldn't have been.

Also fixed a small check in codegen related to FLAG_WIDE and
FLAG_WIDE_CLASS.
Update ref temp removal code to deal with original vars that are refs
Copy a case in codegen from PRIM_MOVE to PRIM_ASSIGN (for no-local)
Change test_nested_var_iterator3 into a bug future

From test_nested_var_iterator3.future:

Bug: Copy propagation can not follow references through record fields

This test started to fail after 4160bf4 (Add peephole optimization to remove
ref temps). The actual failure is due to copy propagation not being able to
follow references through record fields. If this test is run with scalar
replacement, it works correctly since the record fields will be extracted.