swc_ecma_transforms_optimization:
- `expr_simplifier`: Track more changes.
swc_ecma_minifier:
- Analyze after applying the pure optimizer.
- Preserve access to a variable not in scope.
- `compress`: Remove string literal if it was not a directive.
- `pure/collapse_vars`: Merge vars declared in the first statement into one with initializers if `collapse_vars` and `join_vars` are enabled.
- `unused`: Use `usage_count` instead of `ref_count`.
- `unused`: Fix dropping rule for member expressions.
- `unused`: Fix dropping rule for declarations.
- `hoist_props`: Preserve exported items.
swc_ecma_ast:
- Split `MemberExpr` into `MemberExpr` and `SuperPropExpr`.
- Use `Box<Expr>` for `MemberExpr.obj`.
- Use ad-hoc type for `MemberExpr.prop`.
- Use ad-hoc type for `SuperPropExpr.prop`.
- Use `Callee` instead of `ExprOrSpread` for `CallExpr`.
- Simplify types for meta property expressions.
