[analyzer] PR8962 again. Ban ParenExprs (and friends) from block-level...

[analyzer] PR8962 again. Ban ParenExprs (and friends) from block-level expressions (by calling IgnoreParens before adding expressions to blocks). Undo 132769 (LiveVariables' local IgnoreParens), since it's no longer necessary.

Also, have Environment stop looking through NoOp casts; it didn't match the behavior of LiveVariables. And once that's gone, the whole cast block of that switch is unnecessary.

llvm-svn: 132840