This replaces the old --sanity-check flag from dartk. Some files have
been renamed to avoid the wording "sanity check".
Compared to --sanity-check, the following checks have been added:
- variables are not referenced out of scope
- variables are not redeclared
- class type parameters are not referenced from static context
A unit test has been added to check that the verifier rejects certain
invalid ASTs.
BUG=
R=kmillikin@google.com
Review URL: https://codereview.chromium.org/2531873002 .