check arguments of calls to Dynamic against Dynamic so they are not missed
move `is_explicit_null` to type.ml because it is needed in the analyzer
remove some unused code
[cpp] change Reflect.compare implementation to avoid inferred Int types after simplification
consider TVar to be a side-effect
sanitize does not need a typer context
Merge pull request #3412 from Simn/ssa_prepare

SSA preparation part 2