swc_ecma_minifier:
- `if_return`: Allow side-effect-free statements to come after `if_return`.
- `collapse_vars`: Move variables without init to first.
- `analyzer`: Remove useless fields.
- Don't drop `return` tokens if there's a finally block.
- `drop_return_value`: Drop side-effect-free return arguments.
- `make_sequences`: Don't inject `void 0` to return args.
- `if_terminate`: Move to the pure optimizer.
- Fix a bug related to `RegExp`.
