**Description:**
This PR improves the alias analyzer by distinguishing call and reference, thus reducing the number of identifiers.
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Co-authored-by: Justin Ridgewell <justin@ridgewell.name>
**Description:**
As we are not using the return value of the function, we can call `ignore_return_value` on the argument of the return statements of IIFE.
**Description:**
We had two passes for joining variables. This PR removes one in the full optimizer, which is wrong.
**Related issue:**
- Closes https://github.com/swc-project/swc/issues/5989.
